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Threema started life as an abbreviation: “EEEMA,” for “End-to-End Encrypted Messaging Application.” The three “E”s were a bit unwieldy, so it became “Threema.”

Threema is the world’s best-selling secure messenger. It sets itself apart from others in the following respects:

  • Guaranteed privacy: Threema is designed to generate as little data on servers as technically possible.
  • Full anonymity: You are not forced to provide any personal information (such as your phone number or email address) in order to use Threema.
  • Open source: To provide full transparency, the Threema apps are open source. Anyone knowledgeable enough can confirm Threema’s security on their own.
  • Optional contact synchronization: It’s not necessary to grant access to the address book in order to use Threema.
  • Comprehensive encryption: In Threema, all your communications are end-to-end encrypted – not just text messages and voice and video calls but also group chats, media files, and even status messages.
  • Rich functionality: Threema is versatile and feature-rich.

Find out how Threema stacks up against other messengers like WhatsApp, Signal, or Telegram in the comprehensive messenger comparison.

With Threema Work and Threema Gateway, Threema also provides solutions for secure communication in business contexts. 

In contrast to other messengers, your identity in Threema does not depend on a phone number. Each Threema user gets a randomly generated, 8-digit Threema ID when starting the app for the first time. This ID is your unique address in Threema and makes it possible to use Threema completely anonymously, without disclosing any personal information.

Your Threema ID is just one of two components that make up your identity in Threema. The other one is the so called key pair (consisting of a public key and a private key) which is essential for the encryption. Your Threema ID is permanently tied to your public key. While the public key is sent to Threema's servers to be distributed to your chat partners, the private key remains on your device where it is securely stored. All messages directed to you will be individually encrypted with your public key on the sender's device. They can only be decrypted with your personal private key.

Android iOS
Phone iPhone
Tablets iPad
Wearables* (e.g. Smartwatch) Apple Watch*
Android Auto Apple CarPlay

Threema is fully supported.

Threema is not supported.

* If you are using Threema with an Android Wear smartwatch or an Apple Watch, you can read message previews, see chat pictures, agree/disagree to incoming messages and answer messages using dictation (or using Scribble on an Apple Watch).

Threema is currently available in the following languages:

  • English
  • Basque (Spain)
  • Brazilian Portuguese
  • Chinese (Android: traditional; iOS: simplified)
  • Czech
  • Dutch
  • French
  • German
  • Italian
  • Japanese
  • Polish
  • Romansh
  • Russian
  • Spanish
  • Turkish

If Threema doesn’t support the device’s system language, the user’s preferred languages (as defined in the system settings) will be taken into account. If these languages aren’t available in Threema, English serves as fallback.

Is Threema not yet available in your language? Support the translation here:

Threema is tailored to the needs of private users. For business use, we recommend Threema Work.

Yes. Special offers are available for schools, universities, and NGOs:


Threema allows to create a poll right inside a chat. No need to write back and forth when considering several options – initiate a poll with a few taps, and get a useful overview of the received votes.

  • Android: In a chat, tap the paperclip icon, and select “Poll”.
  • iOS: In a chat, tap the plus sign next to the text-input field, and select “Create Poll”.

Check out the promo video.

The agree/disagree feature allows to agree or disagree with an incoming message without triggering a push notification on the chat partner’s device, providing an unobtrusive way of expressing your attitude toward a message.
  • In a single chat, tap and hold on a received message to invoke the context menu.
  • To agree or disagree with the selected message, tap “agree / thumbs up” or “disagree / thumbs down”, respectively.
The agree/disagree feature is not supported in group chats.
With Private Chats, you can protect individual chats and hide them from the chat list. This way, confidential chats are protected from prying eyes. Push notifications for new messages in a private chat contain no message preview.

On Android, navigate to “Threema > Settings > Security > Locking mechanism,” and select “PIN,” “System Screen Lock,” or “Biometric.” On iOS, Private Chats are currently not available.

To mark a chat as private, long-tap on the chat, and select “Mark as private chat.” When attempting to access the chat, the selected locking mechanism (see above) comes into play.

To hide all private chats, tap on the menu icon in the chat list, and choose “Hide private chats”. To show all hidden chats, choose “Show hidden chats” in the chat list’s menu, and enter the PIN.

In Threema, text can be formatted bold, italic, and crossed out. To format text, simply enclose it in the appropriate character:

  • *bold*
  • _italic_
  • ~strikethrough~

This FAQ article covers the QR code that can be displayed in the app (and is used to confirm a contact’s identity and add their Threema ID at the same time; green verification level), not to be confused with the QR code on websites (which can only be used to add contacts; red verification level).

Scanning QR codes is a means for confirming contacts' identities. That way, man-in-the-middle attacks can be effectively prevented: If you receive a message of a confirmed contact (i.e., verification level 3), you can be sure that it wasn't spoofed or read by a third party (provided said contact's device wasn't stolen or hacked). On top of that, scanning someone's QR code is a convenient way of adding them to your contact list without having to manually enter their ID.

Display your own QR code

  • Android: Navigate to the “My Profile” tab, and tap on the QR code icon
  • iOS: Navigate to the “My Profile” tab, and tap on the QR code

Scan a contact’s QR code

  • Android: In the Contacts tab, tap the “New contact” button, and select “Scan ID”
  • iOS: Threema > My ID > camera icon in the top right corner

If you are having trouble scanning a QR code, please make sure the camera is not too close (below 10 in/25 cm), which might prevent it from focussing.

Please note: The QR code of contacts should not be confused with the QR code of ID exports and the QR code used to connect to Threema Web.

Yes. In contrast to other messengers, your identity in Threema isn't tied to a phone number (cf. What is a Threema ID?). Hence, you can use Threema without any limitation on a device that doesn’t have a SIM card slot (cf. Supported Devices).

To save a chat outside of Threema, you can export it as encrypted ZIP archive (which will contain the chat as text file and, optionally, all media files). Please note that exported chats cannot be imported into Threema again; to transfer your chats to another device (or to restore them later on the current device), use a data backup

  • Android: In the chat list, tap and hold a chat, and then tap the “Share” button. You can save or send the chat as an encrypted ZIP file using your installed apps.
  • iOS: In a contact’s or a chat’s detail view, tap “Export Conversation”.

Chat exports are encrypted using the Advanced Encryption Standard (AES). Therefore, a modern file archiver, such as The Unarchiver for macOS or 7-Zip for Windows, is required to unpack a chat export. Some other apps don’t recognize the encryption and return an error message stating that the provided password is incorrect (even though you have entered the password correctly).

Use Threema to send files of any type (PDF, animated GIF, MP3, DOC, ZIP, etc.). Just like all other messages, files are end-to-end encrypted. The maximum file size is 50 MB (it might, however, not be possible to send large files on older devices due to insufficient memory). To avoid compression of an image or video, you can send it as file. Please note: If you send an image as file, its EXIF tags (possibly containing information such as the date and location the image was taken) are preserved.

Android: In a chat, tap on the paperclip icon, and select “File”.

iOS: In a chat, tap on the “+”, and select “Share File”. Due to restrictions of iOS regarding the file system, you can only access content of apps that support file sharing.

Threema is available in a light and a dark theme. You can switch between the two themes here:

Settings > Appearance > Design theme

To quote a text message, tap and hold it until the context menu appears. There, tap the quotation mark icon, and the quoted message will show up above the text input field. (On Android, you can also swipe right to quote a message.) You can then compose and send your message like you usually would. In the chat, the quoted message is indented and prepended to your new message so that it’s evident what you are referring to.

It’s not possible to set up a Threema ID on multiple devices at the same time. You can, however, use Threema Web to connect to the device on which your Threema ID is set up.

A multi-device solution that meets Threema’s strict security and privacy requirements is currently in development; this blog post provides an architectural overview for technically inclined readers.

The only way to use Threema simultaneously on multiple devices is to set up different Threema IDs on each device and create groups containing those IDs as well as the desired chat partner’s ID. Learn more…

If there are unresolved issues in a chat, you can use the “pin” feature to create a visual reminder. Pinned chats always stay on top of the chat list and are marked with a yellow bar. On Android, there is also a pin icon displayed:

  • Android/iOS: In the chat overview, swipe from left to right on a chat to (un)pin it
  • Threema Web: Open the desired chat, and tap the pin icon in the top right corner to (un)pin it

Chats can only be archived in Threema for Android at the moment.

In the chat overview, swipe from right to left on a chat to archive it. The chat will be removed from the chat overview, but not deleted.

To access your archived chats, scroll to the end of the chat overview, and tap the “X archived chats” button.

In order to move an archived chat from the archive back to the chat overview, tap and hold the chat until the action icons appear in the title bar. There, tap the icon next to the trash-bin icon.

To share your current location, open a chat, tap on the paperclip icon (Android) or the plus sign (iOS), and select “Location” (Android) or “Share Location” (iOS).

Security and Privacy

Threema uses state-of-the-art asymmetric cryptography to protect messages and calls between sender and receiver, as well as the communication between the app and the servers. Threema uses the open-source library NaCl  for encryption. Since the Threema apps are open source, anyone knowledgeable enough can confirm Threema’s security on their own.

There are two layers of encryption: the end-to-end layer between the conversation participants, and an additional layer to protect against eavesdropping of the connection between the app and the servers. The latter is necessary to ensure that an adversary who captures network packets (e.g. on a public wireless network) cannot even learn who is logging in and who is communicating with whom.

All encryption and decryption happens directly on the device, and the user is in control over the key exchange. This guarantees that no third party — not even the server operators — can decrypt the content of the messages and calls.

Strength of the encryption: The asymmetric ECC based encryption used by Threema has a strength of 255 bits. According to a NIST estimate (page 54), this corresponds at least with the strength provided by 2048 bit RSA. ECDH on Curve25519 is used in conjunction with a hash function and a random nonce to derive a unique 256 bit symmetric key for each message, and the stream cipher XSalsa20 is then used to encrypt the message. A 128 bit message authentication code (MAC) is also added to each message to detect manipulations/forgeries.

Forward secrecy: Threema provides forward secrecy on the network connection (not on the end-to-end layer). Client and server negotiate temporary random keys, which are only stored in RAM and replaced every time the app restarts. An attacker who has captured the network traffic will not be able to decrypt it even if he finds out the long-term secret key of the client or the server after the fact.

For detailed technical information about the cryptography in Threema, read the Cryptography Whitepaper.

To find out how Threema stacks up against other messengers like WhatsApp, Signal, or Telegram, please refer to our comprehensive messenger comparison.

Comprehensive privacy protection requires solid message encryption, but there is more to it.

Full anonymity

Threema can be used without providing any personal information whatsoever. Instead of a phone number, the Threema ID (a randomly generated eight-digit string) serves as unique identifier. Linking a phone number and/or email address to one’s Threema ID is optional.

Metadata restraint

All data involved in communication other than the actual content is metadata. Serious privacy protection must include both protection of content and protection of metadata. The sole protection of content is insufficient because metadata allows to uniquely identify individuals, analyze their behavior, determine their circles of friends, detect their frequent locations, and monitor their communication behavior. Combined with data from other platforms, the picture that can be drawn of a person is much more detailed than one that could ever be drawn from message contents alone. It’s likely that many messengers are used to systematically collect and analyze their users’ metadata. Threema, on the other hand, generates as little data as technically possible and only stores it as long as absolutely necessary.

Optional contact synchronization

Synchronizing your address book in order to retrieve your contacts’ Threema IDs (provided they have linked them, see above) is optional. If you don’t want to grant access to your address book, you can either scan your contacts’ Threema IDs or add them manually.

In case you enable contact synchronization or link your ID with a phone number or email address, you can rest assured that Threema uses this information only temporarily for the specified purpose. Personal information is always hashed, both in transit and on disk.

To find out how Threema stacks up against other messengers in regard to privacy protection, please refer to the messenger comparison.

Using Threema ought to generate as little data on servers as possible – this is part of the concept. For that reason, data like e.g. contacts or group chats are stored in a decentralized way on user devices, instead of on a Threema server. Our servers assume the role of a switch; messages and data get forwarded, but not permanently stored. Where there is no data, there is nothing to be accessed or misused. However: without some kind of (temporary) data storage, there cannot be any asynchronous communication. In the following we will explain what kind of data we store, how we store it and for how long.

  • Messages and group chats: As soon as a message has been successfully delivered to the recipient, it is immediately deleted from the server. All messages and media are transmitted end-to-end encrypted in Threema. This means: even if someone intercepted your message, it would be completely useless. Only the intended recipient is able to decrypt and read a message.
  • No contact lists are stored when synchronizing contacts: The email addresses and phone numbers from your address book get anonymized (hashed) before they reach the server. Once the comparison is finished, they are immediately deleted from the server.
  • Key pairs are generated in a decentralized way on your device. Your private key is never known to us, and therefore we cannot decrypt any message contents.
  • Threema doesn't log who is communicating with whom (which Threema IDs are communicating).

Further information: Cryptography Whitepaper.

Yes, to ensure full transparency, the Threema apps are open source.

Thanks to reproducible builds, there’s also a way to verify that the published code (of the Android app, for the time being) actually corresponds to the apps available for download in the app stores.

To learn how to download, build, and reproduce the Threema app’s code, please refer to the Open Source subsite.


  • Android: Threema includes its own app-specific encryption based on AES-256 to protect stored messages, media and your ID's private key. The key used for this encryption is generated randomly the first time you start Threema, and can optionally be protected by setting a Master Key Passphrase in the settings, which we highly recommend. Without a passphrase, the encryption will only add obscurity due to the way hardware encryption is handled on Android. If you set a Master Key Passphrase, you will have to enter it after every restart of the device (and after the system has terminated the app due to low memory).

    Note: The PIN lock, which can be enabled independently of the master key passphrase, does not cause any additional encryption; it is simply a UI lock.

  • iOS: Threema uses the iOS Data Protection feature to encrypt messages, images etc. in the device's flash storage. The key used for this encryption is linked to the device's passcode. It is necessary to set a passcode in the system settings to use this feature. On newer models, iOS also uses hardware features for the encryption; therefore even a simple six-digit passcode offers a certain protection. For the highest protection against brute force attacks, you should choose a longer, alphanumeric passcode.

    Note: The passcode lock that is built into the app itself does not offer any additional encryption. This feature is intended to keep nosy people from reading your messages when you intentionally give them your phone for a short time for another purpose. Encryption with a six digit code inside the app would not be sensible, as brute force attacks would be trivial (since unlike iOS, an app cannot access special hardware features to protect the key).

For detailed technical information about the cryptography in Threema, read the Cryptography Whitepaper.

No, that is impossible, as we don't have the secret keys of our users (your secret key never leaves your device). Our servers do need to know who is sending a message to whom, so that they can route it to the correct recipient, but they do not log this information, and cannot decrypt the message's content.

Threema allows to verify that the ID of the person you are communicating with is really theirs.

If you are sure about your chat partner's ID, then there's no way for an attacker to spoof or intercept/decrypt a message from or to your chat partner.

The connection between the app and the servers is secure against MITM attacks because the server authenticates itself to the app based on a public key that is hard-coded into the app and whose corresponding secret key is only known by the legitimate servers.

Please note: Threema can only be as secure as the device that it is running on. Malware that runs in the background on your device can intercept and falsify data without being noticed. We highly recommend to always install the most recent operating system updates and to only use software from trusted sources.

Threema GmbH runs its own servers in two high-security data centers of an “ISO 27001”-certified colocation partner in the Zurich area. 

The state-of-the-art data centers include biometric access control, full-height turnstiles, video surveillance, emergency power systems, fire protection, fail-safe air-conditioning, and a fully redundant Internet connection.

That’s your decision – Threema can be used without any address book access whatsoever.

By default, the synchronization is disabled and no address book data will be read. In this case, you can add your Threema contacts manually (by typing in their IDs or scanning QR codes).

If you decide to enable the synchronization, email addresses and phone numbers from your address book will only be transmitted to the server in one-way encrypted (“hashed”) form and are additionally protected using TLS encryption. The servers only keep these hashes in volatile memory for a short time to determine the list of matching IDs, and then delete the hashes immediately. At no point are the hashes or the results of the synchronization written to disk.

Due to the relatively low number of possible phone number combinations, it is theoretically possible to crack hashes of phone numbers by trying all possibilities. This is due to the nature of hashes and phone numbers and cannot be solved differently (using salts like for hashing passwords does not work for this kind of data matching). Therefore we treat phone number hashes with the same care as if they were raw/unhashed phone numbers.

The Threema apps are open source, allowing anyone to audit Threema’s code on their own. Furthermore, external experts are commissioned to conduct comprehensive security audits on a regular basis. The most recent audits are listed below.

For a comprehensive documentation of the algorithms and protocols used in Threema, please refer to the Cryptography Whitepaper.

During initial setup of your Threema ID, a key pair for the encryption of messages based on Elliptic Curve Cryptography (ECC) is generated. This key generation is performed directly on your phone, without any server interaction. The private key never leaves your device. The random data necessary for key pair generation is obtained from the phone's random number generator and is mixed with further random data that you generate yourself by moving your finger on the screen. This ensures that even if a weakness is discovered in the phone's random number generator, the private keys of the users cannot be cracked.

For more information about the cryptography in Threema, read the Cryptography Whitepaper.

Threema meets the requirements of the European General Data Protection Regulation (GDPR). As a Swiss company, Threema is also subject to Switzerland’s strict Federal Act on Data Protection (DSG) and the accompanying Ordinance to the Federal Act on Data Protection (VDSG).

Threema does not use phone numbers to address users and can be used anonymously without uploading phone book data. It is therefore also suited for childern under the age of 16.

In contrast to conventional messengers, you can therefore be sure to comply with privacy laws when using Threema.

To retrieve your ID’s inventory data that’s stored on the Threema server, simply send “info” to the Threema ID *MY3DATA, and you’ll immediately receive a reply in machine-readable form (JSON).

If you’re reading this page on the device where Threema is installed, simply open the following link, and then tap “Send”:

Explanation of the JSON keys:

  • publicKey: Base64 coded
  • issueDate: date of ID creation
  • lastLogin: date of last login
  • mobileNoHash: hash of linked phone number
  • emailHash: hash of linked email address
  • featureMask: bit mask of features supported by the Threema version in use
    • 0x01: Audio messages
    • 0x02: Group chat
    • 0x04: Polls
    • 0x08: File transfer
    • 0x10: Calls
    • 0x20: Video calls
  • pushtoken/voippushtoken: Push token of the push services in use (GCM/FCM, APNS, WNS)
  • pushsound/pushgroupsound: name of the chosen sound file for push messages (not used on all platforms)
  • revocationKey: information about revocation password, if set

Editable inventory data can be modified or deleted at any time in the Threema app (in the “My ID” tab) with immediate effect (see this FAQ article for more information). To permanently delete your Threema ID’s inventory data, please revoke your ID.


Threema uses the Apple Push Notification Service (APNS) to inform recipients with iOS about new messages while the app is closed or in the background. The APNS message contains a payload that has been encrypted with a symmetric key, which is negotiated between the app and the Threema servers and is not known to Apple.

Within this encrypted payload, the Threema ID and nickname of the sender, the message ID, and the fact whether it is a direct or a group message, are transmitted.

The Threema app is started in the background for each incoming push notification, decrypts the push payload, downloads the corresponding message directly from the Threema servers, decrypts it and shows a local message preview (if enabled) and the contact name of the sender.


Threema uses Firebase Cloud Messaging (FCM) to inform Android users about incoming messages in the background. The app then fetches messages directly from the Threema servers, decrypts them and displays a local notification. Neither contents nor details about messages are transmitted via FCM (the FCM payload is empty), and all of Firebase’s tracking and analysis components have been removed.

You can choose whether or not you would like to use Google services for Threema’s push notifications: The option “Settings > About Threema > Troubleshooting > Activate Polling” allows you to use Threema without FCM. However, we don't recommend this.

The development of a custom push service is difficult because its reliability depends on numerous factors. We are therefore consciously using the recognized push services of Apple, Google and Microsoft. They are already installed on the vast majority of devices. Furthermore, channelling push notifications saves battery power.


Show your friends and family members how easy and convenient secure communication and privacy protection can be. Give away Threema to your loved ones in a few simple steps:


  • Purchase one or more licenses in the Threema shop (There’s no way to give away apps in Google Play.)
  • After succesful payment, you will receive an email containing the license key(s)
  • Distribute the license to your presentee(s), e.g., via email
  • Gift recipients can redeem the licenses here
  • (New versions of the app can be automatically updated using the “About Threema” screen.)


On an iOS device (iPhone or iPad):

  • Look up Threema in the App Store.
  • Tap the Share button
  • In the Share Sheet that appears, tap “Gift App…”, and follow the on-screen instructions

For more detailed instructions, please refer to Apple’s guide.

Moving to a different operating system

Since the different app stores (Apple App Store, Google Play, and Huawei AppGallery) don’t share their license data, Threema has to be purchased again when switching to a different platform.

Important data, such as your Threema ID and your contacts, can be transferred using Threema Safe. Threema Safe backups do not include chats, media files, and profile pictures of contacts and groups.

Reinstalling Threema on the same operating system

Purchase via App Store, Google Play, or Huawei AppGallery

After resetting your phone or switching to a new phone, it may be necessary to reinstall Threema. The App Store (iOS) as well as Google Play and the Huawei AppGallery (Android) allow to reinstall any purchased app at no additional cost. The only requirement is that you use the same store account (i.e., the same Apple ID or Google account, etc.) you used for the initial purchase. The store then will display an “Install” button instead of a “Buy” button. In case you still see a “Buy” button, please follow these instructions.

Purchase via Threema-Shop

If you have purchased the Android version in our store, you can download and then reinstall it with the same license key. If you have lost your license key, you can retrieve it. Please note: Threema versions from the Google Play Store are not unlocked using a license key, and you can't retrieve a license for a Google Play Store version. Because Google Play’s and the Threema Shop’s terms are not identical, licences can’t be transferred between the two sales platforms.

Learn how to move your ID to a new phone.

Paid apps are sold by different providers (Apple, Google, Microsoft). These providers don’t share license data. Hence, it is impossible to move licenses from one platform to another. For this reason, the app has to be purchased again for the new operating system when switching from one platform to another.

Use Threema Safe to transfer your most important Threema data to the new OS.


  • Google Play: For most Android users, this is the best (i.e., most straightforward) way to get Threema.
  • Threema Shop: If you would like to download Threema without a Google account and/or if you would like to pay anonymously with Bitcoin, the Threema Shop is for you.
  • Huawei AppGallery: In case you use a Huawei device that’s not equipped with Google Services, download Threema from the Huawei AppGallery.

iOS (iPhone, iPad, iPod touch)

Download Threema from the Apple App Store.

To learn more about the current version’s changes and improvements, read the change log.

There is no age restriction, and it’s generally safe to use Threema at any age.

EU users who are under 16 years of age are required by law to obtain parental consent if they wish to link a phone number and/or email address with their Threema ID. (If Threema is used anonymously, no parental consent is required.)

The app’s rating in the Google Play Store is determined by the International Age Rating Coalition (IARC). Review certificate…

There is a price plan available for public educational institutions: Threema Education

If you would like to give away Threema as a present to friends or family members, please refer to this guide.

If you would like to use Threema in your organization, please turn to Threema Work, which was specifically designed for this purpose and can be distributed to any number of users without effort.

Schools may use Threema Education, while nonprofit organizations benefit from a special offer.

If you purchase the Threema app from the Threema Shop, you may have to adjust your device’s security settings in order to install and/or update the app.

Android 8 and newer

  • If the dialog “For security reasons, you cannot install unknown apps from this source on your smartphone” is displayed after downloading the APK file from the Threema Shop, tap on “Settings”, and activate “Trust this source”.

Android 7 and older

  • Activate “Unknown sources” in your device’s security settings.
  • It is recommended to deactivate “Unknown sources” once you have installed Threema.

Sending / Receiving

  • message sending Message sending
    The message is being sent to the server. If this status lasts for more than a few seconds, there might be a connection problem. In this case, the message will stay in queue and will be sent as soon as the connection is up again (on iOS, only when the app is open).
  • message sent Message sent
    The message was successfully delivered to the server, and a push notification was sent to the recipient if necessary.
  • message delivered Message delivered
    The message was successfully delivered to the recipient's device; it has not yet been opened by the recipient, but a push notification was displayed. If the recipient has disabled read receipts, this status is permanent and persists even if the message was read.
  • message read Message read
    The message has been read by the recipient. If the recipient has disabled read receipts, this status will not be returned.
  • Senden fehlgeschlagenSending failed
    The message could not be sent. This can happen, for example, when the network connection is interrupted during a file transfer. On iOS, tap and hold the message and select “Try again.”
  • user acknowledgement/user acknowledgement User agreement/disagreement
    The recipient agrees/disagrees with your message. (Learn more about the agree/disagree feature here.)

If the recipient has disabled read receipts in Threema’s privacy settings, messages retain the “delivered” status after they have been read.

A colored stripe (or the absence thereof) below the title bar indicates the connection status:

  • Red: Threema is currently not connected to the server. This is usually due to problems with the Internet connectivity of your phone (e.g., when you have no 3G reception or if you are connected to a broken Wi-Fi network or to a Wi-Fi hotspot that requires login). Threema will keep trying to establish a connection every 10 seconds.
  • Orange: Threema is connecting to the server. A response has been received (i.e., a connection has been established), but the login process has not completed yet. If this status persists for more than a few seconds, it's usually due to a slow or unstable Internet connection.
  • No stripe: Threema is connected to the server. New messages will appear instantly.

If these symptoms occur, either push notifications aren't working properly or there is a problem concerning background activity. Please follow the troubleshooting instructions for Android or iOS.

  • Android: You can insert emoji via the menu next to the text input field. Third-party emoji-keyboards are not necessary.
  • iOS: Unicode emoticons are handled by the system. Go to Settings > General > Keyboard > Keyboards, and activate the “Emoji” keyboard. After that, you can switch to this keyboard while you're typing by tapping the globe symbol.

On Android (all app versions) and iOS (Threema version 2.9.0 and up), incoming messages can be decrypted in the background and presented along with a preview in the push notification. Push preview must be enabled in Threema settings for the preview to be shown.

If there is no Internet connection immediately after a push notification has been received, it is possible that no preview can be shown.

No preview will be shown on Android if:

  • the master key is locked, or
  • PIN protection is activated, or
  • background data is restricted

Contact names

On iOS, if there is no Internet connection immediately after a push notification has been received, it is possible that the real contact name cannot be shown.

If the real contact name cannot be shown, the “public nickname” is displayed instead. By default, it assumes the value of the user's ID, but can be changed anytime. You can ask the sender to use e.g. his or her first name. This will help you recognize the sender of a message.

Problems with sending messages can have different causes. Please proceed as follows:

  1. Please send a message to the ID ECHOECHO. If this works and you receive a response, you're fully able to send and receive messages, and the problem is most likely on the recipient's side.
  2. Make sure that the Threema ID displayed for the contact you want to reach is still actively used by the recipient. The recipient might be using a new ID, in which case messages to the old ID are being misrouted. This can easily be prevented by deleting old IDs and removing duplicate contacts.
  3. Maybe your ID has been unintentionally blocked by the recipient. Ask the recipient to check this in your own contact's details (iOS: Contacts > Contact details > “Block contact” (at the very bottom); Android: Threema > Contacts > Tap and hold on the contact > Settings > “Deblock contact”). Please also make sure that you have not blocked the recipient yourself.

There is a special ID named ECHOECHO that simply echoes back all messages that you send to it. Scan this QR code to verify its key:

echo QR code

Note that in general, QR codes for ID verification should not be sent over the Internet but only scanned from the personal mobile phone of the respective person in order to ensure that there has been no manipulation by third parties.

Messages and files are stored on the servers until they are successfully delivered or until 14 days have elapsed (whichever happens first).

Block single users

If you receive unwanted messages from another Threema user, you can block them:

  • Android: Open the contact details by tapping the contact's profile picture. Then, navigate to “Block contact” in the side menu. Alternatively, you can add the contact’s Threema-ID to the blacklist in “Threema > Settings > Privacy > Blacklist.”
  • iOS: Tap the contact in the contact list and scroll down to the option “Block contact”.

A blocked contact doesn't see if he or she is blocked.

Block unkown

Threema allows you to block messages from unknown users in general. You will find this option in “Threema > Settings > Privacy > Block unknown”.

Please note: When the option “Block unknown” is on, you might not receive messages from your friends if you didn't save their details in your address book or if they didn't link an email address or phone number to their Threema ID. This could make them believe that the sending of messages isn't working properly.

Specific contacts can be excluded from your contact list by using “Threema > Settings > Privacy > Exclusion list”.

Everything you send with Threema is encrypted before sending. This can require a high processor load, especially on older devices. We strive to provide both security and performance to all our users independently of their devices, which is why the sending of videos is currently possible within the following limits:

Android: Irrespective of its duration, the video's file size cannot exceed 50 MB. If you are using Android 4.3 or higher, you can compress videos in Threema > Settings > Media, allowing you to send even very large files, depending on the compression type.

iOS: Videos in high quality can be up to three minutes long; in low quality, videos can be up to 15 minutes long.

Android: To invoke the notification settings of a (single or group) chat, tap the bell icon in the title bar of said chat. The chat can be muted altogether or for a specified duration (and its notification sound can be adjusted, too).

iOS: If you prefer to not receive push notifications for incoming messages of a certain contact or group, open the contact’s or group’s detail view (by selecting the contact or group in the contact list). There, select “Notification settings”. Deactivate the option “Play notification sound” to receive silent push notifications, or set “Do Not Disturb” to “On” in order to not receive push notifications for this contact or group at all.

You will still receive messages in muted chats, but you will no longer be notified about them by push notification (meaning that you have to manually open the app in order to see whether any new messages were sent in muted chats).

Threema transmits messages via the Internet. Aside from Internet connectivity charges (which may vary depending on the mobile network provider), there are no other fees per message.

If you are using Threema behind a Firewall, please make sure that the following TCP ports are open:

  • 5222
  • 443

To make Threema Calls, port 3478 or port 53 needs to be open for outgoing UDP STUN/TURN traffic.

To reliably receive push notifications, the following TCP ports need to be open:

  • 5223 (Apple)
  • 5228-5230 (Google)
  • 443 (Microsoft)

Group Chats

A group chat feature is available. Group chats are handled on each individual device. The Threema servers have no knowledge about group compositions. Groups can contain up to 256 members.

New groups can be created using the “New group” item in the main menu on Android and using the “Compose message” button on iOS. Only those contacts can be selected from the list that have installed a group chat capable version of Threema.


As group administrator, you can delete a group at once, without having to remove all members manually. Please note: After you have deleted a group, other group members can’t use it anymore.

To delete a group, open it, tap on the group’s name in the title bar, open the menu and select “Delete group”,

As a regular group member, you cannot delete a group, but you can leave it. Please note: When leaving a group, the group messages will not be deleted. To leave a group, open it, tap on the group’s name in the title bar, open the menu and select “Leave group”.

To remove the chat from your chat list and delete the chat history, tap and hold the chat, and then tap the trash-bin icon.


Groups created by an iOS user are deleted as soon as the last member has left the group.

To leave a group on iOS, swipe the group from right to left (in the chat list or in the group list), and tap “Delete”.

Only the administrator (i.e., the creator) of a group can add new and remove existing group members.

Open the group details by tapping the group’s profile picture to learn who is the group’s administrator. If you are the administrator, you can add members by tapping “+.”

Like single chats, group chats are end-to-end encrypted in Threema. For privacy reasons, groups are not managed on our servers but directly on users’ devices. Since there is no information concerning group compositions stored on the server, groups can become asynchronous, e.g., if a user restores a data backup or is absent for an extended period of time.

If a group is asynchronous, we recommend resynchronizing it first. Only the group administrator can initiate a synchronization (in the group's detail view). Should the problem persist, please remove the group member due to which the group became asynchronous (see above), and add them again.

You can access a group's detail view as follows:

  • Android: In the group chat, tap on the title bar.
  • iOS: In the group chat, tap on the title bar, and then tap on the bar that appears underneath it (containing tokens of the group members).

If some members cannot see messages in a group chat, it is usually because they have activated the option “Block Unknown”. Disable the “Block Unknown” option in Threema > Settings > Privacy to receive all group-chat messages.

For privacy reasons, groups are not managed on our servers but directly on users’ devices. An ID export only contains the Threema ID and will therefore not suffice to restore groups. A Threema Safe backup, on the other hand, contains also your group memberships (besides other data) and is platform-independent.

Like single chats, group chats are end-to-end encrypted in Threema. For privacy reasons, groups are managed in a decentralized manner on users’ devices, not on a server. Neither is it possible to transfer administrator privileges, nor can administrator privileges be granted to multiple users.

Cloning groups

If a group’s administrator leaves the group, a new group must be created. However, groups can be cloned. If a group member clones a group, they become administrator of a new group consisting of the same members as the original group. The chat history is not transferred to the new group.

  • Android: Tap the title bar in the group chat, then tap the three vertical dots, and select “Clone group”.
  • iOS: In the group chat, tap on the title bar, and then tap on the bar that appears underneath it (containing tokens of the group members). Finally, tap on “Clone group” at the end of the member list.

To mention a group member, perform the following steps:

  • Open the desired group chat
  • Type the “@” character on the keyboard, which will bring up the list of all group members
  • Select the group member you wish to mention; typing additional characters will narrow the list accordingly

Use “@All” to mention all group members.

To learn how to only get notified when you are mentioned, please consult the FAQ article on notification settings for group chats (if you use an Android device) or the article on individual notification settings in iOS.

Default notification settings for group chats

The default notification settings apply to all group chats for which no individual notification settings are defined.

  • Android: In Threema, navigate to Settings > Notifications to adjust the default notification settings for group chats.
  • iOS: In Threema, navigate to Settings > Sound & Notifications to adjust the default notification settings for group chats.

Individual notification settings for group chats

Individual notification settings override the default notification settings and can be adjusted for each group chat separately.

  • Android: Open the desired group chat, tap “⋮” in the top right corner, and select “Notification settings”. Set an individual notification sound for the group chat or mute the group chat (permanently or for a specified duration). If you set “Do not disturb” to “On, unless I was mentioned”, you will only be notified of messages in which you are mentioned. Learn how to customize notification sounds.
  • iOS: Please refer to the FAQ article on individual notification settings in iOS.


The dots are an indicator for a contact's verification level. They don't affect the encryption strength, but are a measure for the probability, that the saved public key of a contact belongs indeed to that contact.

  • Level 1Level 1 (red): The ID and public key have been obtained from the server because you received a message from this contact for the first time or added the ID manually. No matching contact was found in your address book (by phone number or email), and therefore you cannot be sure that the person is who they claim to be in their messages.
  • Level 2Level 2 (orange): The ID has been matched with a contact in your address book (by phone number or email). Since the server verifies phone numbers and email addresses, you can be reasonably sure that the person is who they claim to be.
  • Level 2Level 2 (blue): This verification level is only available in Threema Work; it indicates that the Threema ID belongs to an internal company contact.
  • Level 3Level 3 (green): You have personally verified the ID and public key of the person by scanning their QR code. Assuming their device has not been hijacked, you can be very sure that messages from this contact were really written by the person that they indicate.
  • Level 3 (blue)Level 3 (blue): This verification level is only available in Threema Work; it indicates that the Threema ID belongs to an internal contact whose ID and public key you have verified by scanning their QR code.

The verification levels don't change anything in the encryption strength (it is always the same high-grade ECC based encryption), but they are a measure of thetrust that the public keys saved for your contacts really belong to them. Having the wrong public keys leaves you open to man-in-the-middle (MITM) attacks, therefore it isimportant to verify the keys.

Threema displays only contacts who use Threema. If you know that someone is using Threema, but they are missing or are marked with a red dot, it is because of one of the following reasons:

  • Your contact has not linked his or her Threema ID with a phone number or email address.
  • Your own address book contains neither your contact's phone number nor email address.

If a contact has linked a phone number or email address to their ID that is contained in your address book, the contact shows up in Threema’s contact list (provided that synchronization is enabled) and is labeled with two orange dots.

To start the synchronization process, simply tap on your contact list, drag it down and release it again. To work properly, activate the synchronization feature in Threema > Settings > Privacy. If you are an iOS user, make sure to grant Threema access to your contacts (iPhone Settings > Privacy > Contacts > enable Threema).

Inactive IDs are grayed out

If a Threema ID doesn’t connect to the server for more than three months, the ID is considered inactive and will be grayed out. If the inactive ID connects to the server again, it will (after up to 24 hours) no longer be grayed out. In Settings > Appearance, there’s a setting to hide inactive IDs.

Revoked IDs are struck through

A Threema ID that has been permanently deleted is struck through and considered invalid.

You can get rid of duplicate contacts by deactivating the setting “Show inactive IDs” (Android) or by activating the setting Hide Stale Contacts (iOS) in Settings > Appearance. Stale contacts are IDs that haven't been used for more than three months. Therefore, it might take a while for contacts to be marked as inactive.

Alternatively, you can navigate to a contact’s detail view, activate “Exclude from auto sync,” delete the contact, and it won’t show up again when performing contact synchronizations.

If the contact has been synchronized with the device's address book, simply change the name in the “People/Contacts” app. After the next synchronization in Threema (can be forced by pulling down and releasing the contact list), the new name will be used.

The name of unsynchronized contacts can be changed in the contact details:

  • Android: Tap on the pencil icon.
  • iOS: Tap on “(i)”.
If you use the standard version of Threema, this symbol is displayed next to contacts who use the Threema Work app.

If you use the Threema Work app, this symbol is displayed next to contacts who use the standard version of Threema.

Verification levels are included in both Threema Safe and data backups, they are, however, not included in ID exports. Please create a data backup if your new mobile device runs on the same OS as your old one and you would like to keep your chats. If you would like to migrate your basic Threema data from one OS to another, please use Threema Safe.

If you wish to stay informed about Threema-related topics, you can add the Threema Channel to your contacts and receive interesting news directly within the Threema app. The Threema Channel features several feeds for different topics. You decide which feeds you want to subscribe to, and you can cancel subscriptions at any time.

If you’re reading this page on a device where Threema is installed, simply follow this link (and then tap “Send”) to add the Threema Channel:

To manually add the Threema Channel, add the ID *THREEMA to your contact list, or scan the following QR code:


Then, send the keyword “info,” and follow the on-screen instructions to subscribe the feeds you like.

To unsubscribe from a feed, send “stop [feed name],” e.g., “stop android.”

Mute the Threema Channel if you prefer not to receive push notifications.

In recent versions of Threema, the “ECHOECHO” ID is listed among your contacts by default. It can be used to test message transmission.

You can delete the ECHOECHO contact at any time (and, if need be, add it again manually).

The tilde character (~) in front of a contact’s name indicates that the name is a nickname (e.g. “~Bob”). A user can choose any nickname, which might not correspond to the actual name of said user (e.g. “Robert Smith”).

Threema Safe

Threema doesn’t store your data on a central server, your data is only stored on your local device. This provides the best protection against unauthorized access.

To prevent that your Threema ID, your contacts, and your groups (as well as other data and some settings) are lost if you ever happen to lose access to your device, Threema Safe regularly creates an anonymous and encrypted backup of this data on the Threema server or on another server of your choice.

Threema Safe is platform independent. No matter what Threema version (Android, iOS, or Windows Phone) was used to create a Threema Safe backup, it can be restored on any platform. This allows to conveniently transfer basic Threema data from one platform to another.

Enable Threema Safe

  • Android
    • In Threema’s main screen, open the main menu by tapping the three horizontal dots in the top right corner, and select “Backups”
    • Enable “Threema Safe”, and set a secure password (without this password, you will not be able to restore your Threema Safe backup)
  • iOS
    • In Threema’s main screen, open the “My Profile” tab, and tap on “Threema Safe”
    • Enable “Threema Safe”, and set a secure password (without this password, you will not be able to restore your Threema Safe backup)
  • Windows Phone
    • In Threema’s main screen, tap the three dots in the lower right, and navigate to “Settings > Backup > Threema Safe”
    • Enable “Threema Safe”, and set a secure password (without this password, you will not be able to restore your Threema Safe backup)

Learn how to store your Threema Safe backup on your own server in this guide.

Threema Safe regularly creates a backup of your basic data:

Furthermore, Threema Safe backups contain the following Privacy settings:

Threema Safe backups don’t include chats, media files, and profile pictures of contacts and groups. To save chats, please create a data backup or use the export feature.

Provided that changes were made to the data to be backed up and an Internet connection is established, Threema Safe creates a backup approximately every 24 hours. Each backup replaces the previous one.

You can manually trigger the backup process:

  • Android: Tap the three dots in the top right corner, select “Backups”, and tap “Backup now”.
  • iOS: Navigate to My Profile > Threema Safe, and tap on “Backup now”.

If the Threema app on your device doesn’t connect to the Threema server for 180 days, your backup will be deleted automatically from the server. To manually delete your Threema Safe backup, simply disable Threema Safe in My Backups > Threema Safe.

Threema Safe encrypts the backup data using the password you specify. To derive a cryptographic key from the password, the scrypt algorithm is used. This algorithm is memory- and computation-intensive in order to render brute force attacks challenging. It is, of course, still important to choose a secure password. The compressed backup data is encrypted using the NaCl library, which applies the XSalsa20 and Poly1305 algorithms.

The backup’s file name is also derived from the user’s password. Therefore, the Threema Safe server cannot determine which backup belongs to which ID. Finding (and, of course, decrypting) the backup of a given ID is only possible if the backup’s password is known.

Threema Safe is optional, and you can store backups either on the Threema server or on your own server.

For technical details, please refer to the Cryptography Whitepaper.

Threema Safe backups can be restored in the setup wizard. If there is already a Threema ID set up on your device, delete it first:


  • In Threema’s main screen, tap on “My Profile”
  • Select “Advanced options”
  • Tap “Delete ID”


  • In Threema’s main view, select the “My Profile”/“My ID” tab
  • Scroll to the bottom, and tap on “Delete ID”

In the setup wizard, select “Restore from backup”, and follow the on-screen instructions.

If you don’t remember your Threema ID, you can tap “Forgot your ID?” to retrieve it in case you have linked it to a phone number or email address.

If you don’t remember the password of your Threema Safe backup, there is no way to restore it.

Threema Safe can be used with any WebDAV server (such as NextCloud), provided that the server can be reached via the Internet and is equipped with a valid TLS certificate trusted by the operating system (not self-signed).

To support iOS clients, the server needs to be compliant with the ATS requirements.

Configure the server

  • Create a directory for Threema Safe on your WebDAV server, e.g., /path/to/threema_safe
  • In /path/to/threema_safe, create a text file, name it “config” (without filename extension), and add this content:
  • {
    "maxBackupBytes": 524288,
    "retentionDays": 180
  • In /path/to/threema_safe, create a writable directory called “backups”

Please note that we cannot provide support for server setup and configuration.

Configure the app

  • Android:
    • In Threema for Android’s main view, tap “⋮” in the top right corner, and select “Backups”
    • Activate “Threema Safe”, and tap on “Expert Settings”
    • Deactivate “Use default server”, and enter the URL to your Threema Safe directory (as defined above), e.g., If your server requires HTTP authentication, please specify your username and password.
  • iOS:
    • In the “My Profile” tab, select “Threema Safe”
    • Activate Threema Safe
    • Deactivate “Use default server”, and enter the URL to your Threema Safe directory (as defined above), e.g., If your server requires HTTP authentication, please specify your username and password.

There is no way to reset your Threema Safe password if you don’t have access to your mobile device (e.g., in case of loss). If you have access to the mobile device where your Threema ID is set up, you can change the password as follows:

Android: Open Threema, and open the main menu by tapping the three horizontal dots in the top right corner, and select “Backups.” Then, tap “Change Password.”

iOS: Open Threema, and navigate to “My Profile > Threema Safe,” and tap “Change Password.”

ID Export and Data Backup

Every user creates a unique, random Threema ID when setting up Threema for the first time. If you lose your smartphone or buy a new device, you need an export (i.e., backup) of your Threema ID. We recommend to immediately enable Threema Safe or create an ID export after creating a new Threema ID.

  • Create an ID export on your previous device: Tap on “My ID”, then select “ID export”, and activate the option “Include in phone backup” after exporting your ID. Make sure to store this password in a safe place; without it, you won’t be able to restore the exported ID.
  • Transfer your data using Quick Start from your old to the new device (or create an encrypted iTunes or computer backup of your old device, and restore it on your new device).
  • When starting Threema for the first time, tap on “Restore from Backup”, select “Keep local data”, and tap “ID Export”. The ID-export string is prepopulated. What’s left to do for you is to enter the ID export’s password and to confirm by tapping “Done”.
  • Delete your ID on your old phone to make sure you receive notifications on the new device: On your old phone, open the My Profile tab, and select “Delete Data and ID.”

To restore a Threema ID, you need an ID export (or a Threema Safe backup). It consists of 80 digits and letters in groups of four characters (separated with dashes). You string is shown in two ways when exporting an ID: as plain text for copying/pasting and as a QR code.

In the restore menu, you can either enter the long string manually, or you can scan the QR code. Restoration is only possible with an ID export. If you mistakenly scan a public Threema ID, you will see a long string after scanning that starts with “3mid:”. Restoration will not be successful in that case. Please ensure that you are using an ID export for restoration.

We have no access to your data. If you would like to restore your ID, messages or contacts, you need both a backup and the associated password. If some of the information is missing, your data is not accessible anymore. We can provide you with the following general recommendations:

  • Ask your chat partner if he or she can send you the messages/media files once more, or if he or she can export the conversation as a text file.
  • Adjust Threema's settings to automatically save incoming media files to the standard media folder of your operating system. This will keep these files accessible to you even if you delete the app.
  • Create a PIN lock for your app, e.g. to protect your ID in case of theft of your device.

Verification of the email address

Emails might get stuck in spam filters, so please check your spam folder, and please be patient. Some ISPs use greylisting, which causes emails from new senders to be delayed by up to an hour.

You can try again (perhaps using a different email address) by going back to the “Linked Email” dialog, clearing the address and saving. This will reset the status, and you will be able to try again.

Verification of the phone number

We make a best effort to deliver text messages to all countries. If you don’t receive the verification message, this might be due to a temporary problem or because your carrier filters certain messages. Threema offers the option to request the verification code via a phone call:

  • On Android, a green banner is displayed on the main screen during pending verification; tap “Enter Code” and then “Request call”. Please note that a phone call can only be requested after the SMS reception timeout (of approx. one minute) has elapsed.
  • On iOS, simply go back to the “Linked Number” dialog and choose the call option.

Please understand that we cannot call certain countries/numbers.

Note: You can use Threema while the email verification and/or the SMS verification is pending. You can also choose to use Threema without providing a phone number and email address. In this case, however, others need to know your ID in order to contact you.

Remove Threema ID from current device

Would you like to remove your Threema ID from the current device in order to create a new ID or to restore a backup? Delete your ID in the “My Profile” section in the Threema app. When starting Threema the next time, you can use the setup wizard to create a new ID or to restore a backup.

Please note: When deleting your Threema ID as described above, the ID will only be removed from the current device. In case the ID also set up on another device, it will not be deleted there. Also, the deleted ID can still be restored if a backup was created.

Permanently delete your Threema ID

If you should ever happen to lose access to the device on which your Threema ID is set up (e.g., if the device is stolen), you can revoke your ID only if an ID revocation password was set. Set an ID revocation password here:

  • Android: My Profile > ID Revocation
  • iOS: My Profile > ID Revocation Password

Without access to your ID or without a previously set revocation password, it is not possible to delete the ID. However, the ID will be marked as inactive automatically after three months of inactivity.

If you revoke your ID, other users will be unable to send messages to this ID after about one hour. Within 24 hours, the ID will be crossed out (or hidden, if Hide Stale Contacts is enabled) on your chat partners’ contact lists.

In contrast to other messengers, your identity in Threema is not dependent on a phone number. Irrespective of the SIM card / phone number you're using or in which country you are, your Threema ID stays the same and everyone can still reach you. Your existing chats are unaffected by a change of your phone number as well.

Do you have a new phone number and don't want to use the old, linked one anymore? Simply delete the old number on the “My Profile” tab and type in the new one — your ID is now linked to the right number.

If you link your new Threema ID to the same phone number or email like the previous ID, your contacts might see your name twice. You can fix this as follows:

  1. Link your new ID with the same email address and phone number as your old ID. This will cause the link of the old ID to be removed, since every email address or phone number can only be linked to one ID at a time.
  2. Ask your chat partners to delete your old ID from their contact list. It will not be found during synchronization anymore as the links have been removed.
  3. If you were a member of group chats, please ask the respective administrators to remove your old ID and add the new one. If you were a group administrator yourself, the groups in question must be re-created or cloned by existing group members.

If you cannot or prefer not to create a new ID, you can also unlink your old ID.

Read here how you can get rid of duplicate contacts in your own address book.

When you switch your device (or reset it to factory settings), you can transfer (or restore) your Threema ID and continue to use the app as usual. To transfer your ID, you need a Threema Safe backup.

Alternatively, you can create an ID export. A data backup also contains your ID, but it can only be restored on the same operating system it was created on (i.e., you can’t restore a data backup that was created on Android on iOS, or vice versa). It’s recommended to create a Threema Safe backup.

Threema Calls

Threema calls impress with crystal-clear voice quality and brilliant video quality. Since they are end-to-end encrypted, they are tap-proof. Instead of a phone number, the Threema ID serves as unique identifier.

  • The call connection is established using Threema messages in the background; therefore, voice calls are just as trustworthy as chats, and the same verification levels apply
  • If possible, a direct connection between caller and callee is established (peer to peer) after the connection buildup
  • Calls with verification level 1 (red) IDs are routed through the Threema server in order to obscure the IP address (in “Settings > Threema Calls,” there’s an option to route all calls through the Threema server)
  • Because a constant bit rate is used for audio encoding, no conclusions about the content can be drawn from the size of the transmitted data packets
  • Video transmission is an option of Threema calls that can be enabled at any time during an ongoing call. Once a Threema call is established, both parties can independently enable and disable video transmission by tapping the camera icon.
  • Thanks to Threema’s contact verification, Man-in-the-Middle attacks can be effectively prevented, and there’s no need to manually verify a code for the purpose of authentication

For detailed technical information in regard to Threema calls’ security, please refer to the Cryptography Whitepaper.

To place a Threema call, the following system requirements must be met by both the caller’s and the callee’s device:

  • Android
    • Voice calls: Threema 4.22 for Android or above on Android 4.1 or above
    • Video calls: Threema 4.4 for Android or above on Android 4.4 or above
    • To receive calls when Threema is in the background, Google Play Services are required.
  • iOS
    • iPhone: Threema 3.0 for iOS or above (voice calls) or Threema 4.6 for iOS or above (video calls) on an iPhone 5s or above running on iOS 10 or above
    • iPad: Threema 3.0 for iOS or above (voice calls) or Threema 4.6 for iOS or above (video calls) on an iPad Pro, an iPad Air, a 5th-generation iPad or above, or a 2nd-generation iPad Mini 2 or above running on iOS 10 or above

Establish a voice call

Select the desired contact in your contact list, and tap the phone icon in the title bar (Android), or tap “Threema call” (iOS). Alternatively, tap the phone icon in a chat’s title bar.

Enable video

Video transmission can be enabled at any time during an ongoing call. Once a Threema call is established, both parties can independently enable and disable video transmission by tapping the camera icon. This is to say that it’s possible to conduct one-way video calls.

Please note that the system requirements must be met by both the caller’s and the callee’s device in order to make voice or video calls.

Completely disable Threema calls: Navigate to “Threema > Threema Calls,” and disalbe “Threema Calls.”

If you disable Threema calls, no one can call you via Threema, and you can’t call anyone.

Don’t allow video calls: Navigate to “Threema > Threema Calls, and disable “Allow Video Calls.”

If you don’t allow video calls, no one can send their video to you, and your can’t send anyone you video.

While a voice call is ongoing, approximately 750-800 KiB of data is transferred per minute.

The bit rate of video calls depends on the available bandwidth and the image quality.

If you hear your own voice as an echo during voice calls, the echo cancellation doesn't work correctly on your call partner’s device, and the sound from the earpiece is sent back to you through the microphone. Please ask your call partner to change the Echo Cancellation in About Threema > Troubleshooting (form “Hardware echo cancellation” to “Software echo cancellation” or vice versa).

Threema calls are as secure as Threema messages. Just like Threema messages, voice calls and video calls are end-to-end encrypted. The call connection is established using Threema messages in the background; therefore, Threema calls are just as trustworthy as chats, and the same verification levels apply.

Instead of a phone number, the Threema ID is used as unique identifier. This allows you to make end-to-end encrypted voice or video calls without disclosing your phone number.

Learn more about Threema calls here.

Ringing: The phone is ringing at the recipient’s end.

Busy: The recipient either rejected your call or is already talking on the phone to someone else.

Pickup: A connection has been established; you can talk to the callee.

Hangup: The connection was dropped.

Problem: The connection has been interrupted; an attempt to re-establish the connection is in progress.

The image quality of video calls depends on the available bandwidth and the settings of your call partner. In case of a poor network connection, the image quality is automatically lowered.

The preferred image quality can be adjusted in Threema > Settings > Video Calls > Preferred Image Quality. The following options are available:

  • Balanced (Recommended): High image quality in Wi-Fi, reduced data consumption in the mobile network
  • Low Data Consumption: Reduced image quality
  • Maximum Quality: Warning: This setting can cause considerable data consumption!

If you and your call partner prefer a different image quality, the lower quality will be used. If, for example, you have set Maximum Quality as preferred image quality, this image quality will only be used if your call partner has also set Maximum Quality as preferred image quality.

Profile Pictures

In Threema, you can set a profile picture that represents you in your chat partners’ contact lists. You can fully control who is allowed to see your profile picture. Set a profile picture as follows:

  • Android
    • Open the “My Profile” tab
    • Tap the arrow next to your Threema ID
    • Tap the avatar icon (or the current profile picture if one is already set)
    • Choose between “Take photo” and “Select from gallery”
    • Crop the image you have selected, and confirm by tapping “Save image”
    • To choose who is allowed to see your profile picture, tap “Release profile picture to”

  • iOS
    • Navigate to the “My Profile” tab, and tap on the avatar icon (or the current profile picture if one is already set)
    • Tap “Pick image” (or tap the current profile picture if one is already set), and select an existing picture, or snap a photo
    • Crop the image, and confirm by tapping “Choose”
    • To choose who is allowed to see your profile picture, tap “Release profile picture to”

For privacy reasons, profile pictures are not stored on a server, they are transmitted between users upon message exchange and are end-to-end encrypted.

The next time you send someone a message, your profile picture will be transmitted automatically (provided your settings allow it). Alternatively, you can transmit your profile picture manually to a contact by tapping “Send profile picture now” in the contact’s detail view.

If a contact has disabled profile pictures, your profile picture will not be displayed in their contact list and chat overview.

To remove your profile picture, proceed as follows:

  • Android
    • Open the “My Profile” tab
    • Tap on the arrow next to your Threema ID
    • Tap on the avatar icon (or the current profile picture if one is already set)
    • Select «Remove image»
  • iOS
    • Navigate to the “My Profile” tab, and tap on your current profile picture
    • Tap on your current profile picture once again, and select “Delete Photo”

For privacy reasons, profile pictures are not stored on a server. The next time you send someone a message, your profile picture will be removed automatically on the recipient’s end. Alternatively, you can immediately remove your profile picture from someone’s contact list by tapping “Send profile picture now” in the contact’s detail view.

Should you prefer to use your own contact pictures (or if you wish to not display contact pictures at all) instead of the profile pictures your contacts have set for themselves, navigate to Settings > Appearance, and deactivate “Show profile pictures”.

If “Show profile pictures” is enabled, your contacts’ profile pictures are displayed no matter if you have set contact pictures for them in Threema or in your operating system’s address book.

If a contact picture is set for a contact in Threema or in your operating system’s address book, this picture will only be displayed in Threema if “Show profile pictures” is deactivated or if the contact in question hasn’t set a profile picture (or doesn’t share it with you).

If (for some contacts) no profile pictures are displayed in the chat overview and in the contact list, this might be due to one or more of the following reasons:

  • Profile pictures are disabled (in Settings > Appearance).
  • The contacts in question haven’t set a profile picture, or they don’t share it with you.
  • The contacts in question didn’t send you a message since setting their profile picture (profile pictures are transmitted upon message exchange).


If you experience problems with push notifications, i.e., if incoming messages show up late or only when opening the app (and/or if you are unable to re-establish a connection to Threema Web), the reason usually lies in restrictions imposed by the device maker.

In such cases, the Threema app doesn’t have permission to be active in the background and/or to transmit data in the background. Please grant the required permissions as follows:

  1. In Threema, navigate to “Settings > About Threema > Troubleshooting > Fix device configuration problems”
  2. Select “Disable power restrictions” (if available), and follow the on-screen instructions
  3. Select “Enable background data” (if available), and follow the on-screen instructions

Should the problem persist after making these adjustments, please follow the device-specific troubleshooting instructions.

The latest Threema version for Android requires Android 4.4 or above.

Here is an explanation of the most important permissions that Threema for Android requires:

  • Read/write contacts
    Required for address book synchronization. If the synchronization is off, contact data is not accessed.
  • Camera
    Required for contact verification via QR code and for the built-in camera app.
  • Microphone
    Required for Threema calls and voice messages.
  • Location
    Used for the “Send location” feature.
  • Accounts
    Used for contact synchronization resp. integration into the account management of Android.
  • Modify or delete the contents of your USB storage
    Required for reading and storing media files (images, videos, documents).
  • Make and manage phone calls
    Required to reject incoming phone calls while a Threema call is ongoing.

Yes, if you buy the app from the Threema Shop, you don’t need a Google account.

You can also use Threema without Google Play Services. In this case, you will not receive push notifications, but using Threema’s “polling” feature you can still get notified about incoming messages.

If you use a Huawei device that’s not equipped with Google Services, you can download Threema from the Huawei AppGallery.

This problem only affects the Android version of Threema under specific versions of the Android operating system.

Some Android versions (Jelly Bean 4.1.1 is usually affected, and on some Samsung devices even more recent versions) have a bug that affects paid apps. The sync account is lost after rebooting the phone; consequently, the contact synchronization does not work anymore. We're currently searching for a reasonable workaround and recommend all users to update to a newer operating system version if possible.

As a temporary solution, you can turn the synchronization off and on again in the Threema settings. This will cause the account to be recreated and the synchronization will work again until the next phone reboot.

More information on this Android bug can be found here.

You might be experiencing issues with Threema after upgrading your phone's operating system or making other changes to your phone. In such a case it might be necessary to reinstall the app. To avoid a losing your data, please follow the steps below:

  1. Create a data backup in Threema including media files (find out how).
  2. Go to Android > Settings > Apps > Threema.
  3. Tap on “Delete data” and uninstall the app.
  4. Reboot your phone and reinstall the app.
  5. Open Threema and restore the previously created backup with our setup wizard.

Did you purchase Threema in the Google Play Store, but can't see updates or an install button in the Google Play Store? Please proceed as follows:

  1. Make sure you are using the same Google Account as when you purchased Threema.
  2. On your computer, log into Navigate to Apps > My Apps. Does Threema appear in this list?
  3. If Threema is listed, delete the data of your Google Play Store and Download Apps on your phone according to these instructions.
  4. Restart your phone and log in to the Google Play Store. You can now proceed with the update or reinstallation of Threema.
  5. If Threema is not listed in My Apps, you were using another Google Account when you purchased Threema, or you bought it in our own shop.

Android automatically quits background tasks if you are low on memory space. This might affect a process which is responsible for keeping the passphrase present in memory. You must re-enter your passphrase when starting up Threema. Threema cannot change this.

If you are frequently asked to provide your passphrase, we recommend you to disable it and use global encryption on your device instead. You can find this in your phone's settings: Security > Encrypt phone or Security > Encrypt device.

This notification is shown if you're using the Android version of Threema and have set a passphrase on your master key. In order to prevent the operating system from terminating the Threema process (which would cause the unlocked master key to be lost as it is only held in RAM, necessitating manual re-entry of the passphrase), the app needs to show a notification. This notification has no other purpose and is only required because of the aforementioned limitation of Android.

Please note: in times of extreme memory shortage, Android will even terminate processes that show a persistent notification. In that case, it is possible that you are prompted for the master key passphrase again. This is caused by Android; Threema has no influence on this process termination.

Save individual (media) files manually

First, tap-and-hold the desired (media) file in the chat; then, tap the floppy disk symbol.

Starting with Android 10 and Threema 4.5 for Android, (media) files are saved in the following directories, depending on the file type:

  • Pictures/Threema
  • Movies/Threema
  • Music/Threema
  • Documents/Threema

On Android 9 and below, the media files are saved in the directory “Threema/Threema Pictures” (or “Threema Videos”/“Threema Audio,” depending on the file type). Files are saved in the device’s global “Download” directory and can be accessed using the Downloads app.

Automatically save incoming media files

In Threema, navigate to “Settings > Media & Storage,” and activate “Auto-save to gallery.” Automatically saved media files are located in the same directories as manually saved media files, see above.

On Android, distribution lists can be used to send messages to multiple recipients. In contrast to group chats, messages are sent to the recipients separately when using distribution lists. Thus, the recipients are unaware of the fact that other recipients have received the same message. Sending a message to a distribution list is essentially the same as sending the message to each member of the distribution list in a single chat.

To create a distribution list on Android, proceed as follows:

  • In Threema’s main screen, open the menu (by tapping the three horizontal dots in the upper right corner), and select “New distribution list”
  • Select the recipients who shall receive messages sent to this distribution list, and conclude your selection by tapping the check mark in the top right corner
  • Specify a name for the distribution list, and confirm by tapping “OK”

The notification priority can be adjusted in Threema > Settings > Sound & Notification > Priority. This setting controls how prominently notifications are displayed. The default is High and should not be changed. Adjustments to this setting may have different effects on different devices and on different Android versions. In general, the setting Low should prevent popup notifications from being displayed.

Starting with Android 8.0, apps are required to assign their notifications to so-called “notification channels”. These channels determine which signals (notification sound, light, vibration, etc.) incoming notifications trigger.

For privacy reasons, Threema doesn’t create a separate notification channel for each contact but one for each combination of notification settings. A channel’s ID is a hash of its notification settings.

Editing notification settings

Only edit notification settings for chats and calls in Threema (in Settings > Sound & Notifications or in a chat’s individual notification settings), not in the system preferences. Changes made in the system preferences will be lost.


If you use a Xiaomi device (including Pocophone) running MIUI 10 or later, please enable notification signals as outlined in this guide.

To use custom ringtones and notification sounds on Android, please perform the following steps:

  1. Copy your ringtone sound files to the folder “ringtones” and notification sound files to the folder “notifications”. Alternatively, you can use third-party apps like Ringtone Maker, which will take care of copying the files to the correct location for you.
  2. In the Threema app, navigate to Settings > Notifications, where you can now select the sound files you have just added.


In MIUI 11, some notification settings are disabled by default for Threema, and, unfortunately, there’s no way for the app to enable them. However, you can adjust these settings as follows:

  • In Threema, navigate to Settings > Sound & Notifications
  • Tap on “MIUI settings”
  • Enable all (or the desired) notification settings for Threema:
    • Show notifications
    • Show app icon badges
    • Floating notifications
    • Lock screen notifications
    • Allow sound
    • Allow vibration
    • Allow using LED light


If an app like Threema creates a notification channel in MIUI 10, only vibration can be enabled as notification signal, all other signals (heads-up, sound, notification light, etc.) are disabled by default and must be enabled manually.

Please enable notification signals as follows:

  • In Threema, navigate to Settings > Sound & Notifications
  • Select “MIUI Settings”
  • Open the first entry in the Chats section
  • Enable all settings (Floating Notifications, Lock Screen Notifications, Sound, etc.)
  • Return to the previous screen, and repeat the procedure for all other entries in the Chats section

When a new notification channel is added (i.e., when you start using a new combination of notification settings), you will also need to enable that channel’s notification settings as outlined above.

Due to restrictions by Xiaomi, there is no way for Threema to automatically adjust the notification-channel settings for you. For some selected apps, Xiaomi has enabled all notification signals by default. Please get in touch with Xiaomi to learn more.

Due to its low reliability, “Android Backup” is no longer available in Threema 3.6 for Android and above. Please use Threema Safe and/or create data backups.

Starting with version 4.0, there’s a camera built into Threema for Android. To open it, tap the camera icon in the text field. The built-in camera covers basic functionality. You can, however, still use an external camera app if you would like to use special features: Tap on the paperclip icon in the text field, and select “System Camera”.


If you have accidentally answered “No” when asked whether you want to allow Threema to access your photos, you can grant permission as here:

iOS Settings > Privacy > Photos > Threema

If Threema is not listed in the location mentioned above, please remove restrictions for Threema:

  • iOS 12: iOS > Settings > Screen Time > Restrictions > Photos > Allow Changes
  • iOS 11 and earlier: iOS > Settings > General > Restrictions > Photos > Allow Changes

Please perform the following steps to troubleshoot problems with push notifications (and/or if you’re having trouble re-establishing a connection to Threema Web) on iOS:

  • Navigate to to “iPhone Settings > Notifications > Threema”. Ensure that badges, alerts and sounds are turned on.
  • Turn off your phone.
  • Turn your phone back on.
  • Open Threema and wait for 30 seconds in order for it to re-negotiate push notifications with the server.
  • Push notifications should now be working.
  • If only a certain contact is affected by the push issue, please make sure that push notifications for the contact in question are not disabled (navigate to the contact details, scroll down, and choose the option “Off” in “Notification settings > Do not disturb”).

Also make sure you’re not connected to a Wi-Fi network that blocks the ports that Apple uses for push notifications (try turning off Wi-Fi to see if push notifications work).

Please note that push notifications have to be delivered using the APNS service from Apple. Threema cannot influence the reliability of this service and cannot solve any issues with APNS. Issues that you notice with push notifications in Threema might be caused by the APNS service.

If the steps above did not resolve the issue, please get in touch with Apple’s support. If Apple is unable to help, the issue can be resolved by re-installing the app as described in our guide on advanced push notification debugging as a last resort.

In some cases (e.g., when the memory usage is high or the battery level low), incoming push notifications can’t be decrypted in the background. In these rare cases, a generic notification (“Message” or “Group Message”) will be displayed.

There are two ways to share files using Threema on iOS.

Select the files in Threema: In a conversation, tap the plus sign (“+”) next to the input box, and select “Share File”. Then, choose the app that hosts the file you would like to share (e.g. Contacts), select the file, and confirm by tapping “OK”.

Select the files in another app: In the app of your choice, select the file you would like to share, tap the Share Button, choose “Open in Threema” (depending on the app, you might need to tap “Open in…” first), select the contact you would like to send the file to, and confirm by tapping “Send”.

The latest version of Threema runs on iOS 10 and up. You can continue to use older Threema versions on your pre-iOS 10 device, but you won't be able to update to newer versions.

Older Threema versions don’t support all the features newer versions provide, and it’s advisable to install the lastest Threema version whenever possible.

Here are the last supported Threema versions for each iOS version:

  • iOS 5: Threema 2.4.2
  • iOS 6: Threema 2.5.0
  • iOS 7: Threema 2.6.2
  • iOS 8: Threema 2.10.2
  • iOS 9: Threema 4.2.3

The effort needed to offer compatibility with older iOS versions is substantial. For this reason, we need to drop support for older iOS versions from time to time when we release larger updates.

In Threema, navigate to Settings > Chat > Font Size to adjust the font size. If “Use system font size” is selected, the system-wide setting in iOS Settings > Display & Brightness > Text Size will be used.

Adjust the notification settings of a single or group chat like this in the iOS app:

  • Open the desired chat, and tap the title bar. Then, tap the bell (or “Stop” or “@”) symbol in the bar that appears below the title bar to open the notification settings.
  • Activate “Do Not Disturb” to disable notifications (for a certain duration). In group chats, the option "Notify when mentioned" is available: If activated, you will only receive notifications for messages in which you are mentioned.
  • Deactivate “Play notification sound” to mute notifications; you will still receive notifications, but no notification sound is played.

This message is related to the Family Sharing feature of iOS; Threema does not have any influence on it. However, problems with Family Sharing can usually be solved by offloading and reinstalling the affected app.

Go to iOS Settings > General > iPhone Storage > Threema and choose “Offload App”. When this has completed, start Threema again. The system should automatically reinstall Threema without losing any data.

In and of itself, Threema does not provide an option to save chats on iCloud. If, however, you have chosen to save device backups on iCloud, all app data, including Threema chats, will be stored on iCloud.

Neither is there a way for third-party apps like Threema to control this behavior, nor can such apps detect whether iCloud device backups are enabled or not. Even though apps can exclude individual files from backups, these files are excluded from all backups, also from encrypted iTunes backups. Therefore, we recommend to either create iTunes backups instead of iCloud backups or to exclude Threema if you must create iCloud backups.

Threema Work admins can use the MDM parameter th_disable_system_backups to prevent iCloud and iTunes from including Threema Work data in backups. As mentioned above, it is, however, not possible to only allow iTunes backups.

To learn more about security aspects of iCloud backups, please refer to this Apple article.

Threema Web

Threema Web ( is Threema’s web client. It allows you to use Threema on the desktop without compromising security. 

  • Complete synchronization: By scanning a QR code, desktop and mobile device are connected at once, and all conversations are fully accessible on the desktop.

  • Security and data restraint: All communication between phone and PC is fully end-to-end encrypted. After the session is terminated, all synchronized messages are immediately deleted in the browser.

  • Open Source: Like the mobile apps, Threema Web is open source and uses open standards. It’s also possible to host Threema Web on your own server.

All you have to do to use Threema Web is connect your mobile device with your browser.

For detailed technical information in regard to Threema Web’s security, please refer to the Cryptography Whitepaper.

  1. On your computer, open (with a supported browser)
  2. In the Threema app, select “Threema Web” and activate the scanner:
    • Android: Main menu > “Threema Web” > "Initiate new Session" / QR code symbol
    • iOS: “Settings” > “Threema Web” > camera icon in the top right corner
  3. Use your mobile device to scan the QR code displayed on

Hint: To avoid having to scan the QR code each time you use Threema Web, set a session password in the browser before scanning.

The following browsers are supported:

Threema for Android Threema for iOS
Apple Safari 0 1
Chromium 1 1
Google Chrome 1 1
Microsoft Edge 1 1
Mozilla Firefox 1 1
Opera 1 1

Threema Web currently provides the following features:

  • Full access to all contacts, media and chats, including past conversations
  • Send/receive text messages, pictures and media
  • Send/receive files (send files using drag and drop)
  • Send/receive emoji
  • Play animated GIFs
  • Agree/disagree feature
  • Add contacts
  • Manage groups and distribution lists
  • Set a session password

To use Threema Web without having to scan the QR code each time, you can set a session password.

On, enter a session password before scanning the displayed QR code. To use Threema Web the next time on the same computer, you can simply enter this password (instead of scanning the QR code again).

This way, it’s also possible to use Threema if your mobile device isn’t present (provided it’s connected to the Internet).

The different sessions are listed in the Threema app, where you can remove and rename them.

These are Threema Web’s main characteristics and advantages:

  • Threema Web allows to use Threema on the desktop without compromising security
  • Threema Web reduces the digital footprint to the bare minimum by establishing a direct connection between desktop and mobile device (Android)
  • No mirroring of the user’s message database – neither on a server nor on the desktop
  • Since Threema Web is web-based, it is platform-independent
  • Threema Web is open source
  • Threema Web uses WebRTC, a tried and tested open standard for direct communication between two devices (Android)
  • SaltyRTC ensures a secure connection between browser and mobile device (Android)

Threema Web establishes an end-to-end encrypted connection between web browser and mobile device. Once the session has ended, all synchronized messages are deleted in the browser. Threema Web acts merely as extension of the mobile app and hence meets Threema’s high security standard.

The technical details of Threema Web’s architecture are documented here.

Threema Web is currently available in English and German. If German is set as preferred language in the browser, German is used; English is used in all other cases.

If establishing a connection to Threema Web freezes at 60%, it’s not possible to connect browser and mobile device using WebRTC.

Please make sure you are using the latest version of a compatible browser.

Verify that no browser plugin (such as an ad blocker) is disabling WebRTC, and reload Threema Web.

If you are behind a (corporate) firewall or are using a VPN, Deep Packet Inspection might block WebRTC.

If sessions are not saved despite using a session password, browser settings might prevent the data necessary for restoring sessions from being stored locally.

Please adjust your browser settings as follows:

Chromium/Google Chrome

  1. Enter “chrome://settings/content/cookies” in the URL bar, and press Enter
  2. Add “” as hostname pattern, and set “Allow” as behavior
  3. Restart Chromium/Google Chrome

Mozilla Firefox

  1. Enter “about:preferences#privacy” in the URL bar, and press Enter
  2. If, in the “History” section, “Never remember history” is set, change this setting to “Use custom settings for history”
  3. Click the “Exceptions” button next to “Accept cookies from sites”
  4. As “Address of website”, enter “”, and click “Allow” and then “Save Changes”
  5. If (in the “History” section) “Clear history when Firefox closes” is activated, click the “Settings” button; if “Cookies” is checked, uncheck it and confirm by clicking “OK”
  6. Restart Firefox

In order for Threema Web to display desktop notifications, the respective permission must be granted in the browser. If this permission was denied initially, it can be granted later as follows:

Chromium/Google Chrome

  1. Close Threema Web
  2. Insert “chrome://settings/content” in the URL bar, and press Enter
  3. Under “Notifications”, click “Manage exceptions”
  4. Change the Behavior of “” from “Block” to “Allow”
  5. Open Threema Web


  1. Close Threema Web
  2. Insert “about:preferences#privacy” in the URL bar, and press Enter
  3. Under “Notifications”, click “Choose…”
  4. First, select “”; then, click “Remove Site“ and “Save Changes”
  5. Open Threema Web, and grant permission to send notifications


  1. Close Threema Web
  2. Insert “opera://settings” in the URL bar, and press Enter
  3. First, click on “Websites”; then, under “Notifications”, click “Manage exceptions…”
  4. Change the Behavior of “” from “Block” to “Allow”
  5. Open Threema Web

The connection between Threema Web and the mobile device is usually stable. If you use an Android device and the connection is interrupted on a regular basis, please connect your computer and your mobile device to the same local network, if possible. Please check also if you are using the latest app version, and update the Threema, if necessary.


On Huawei and Xiaomi devices, the OS closes the connection between the web browser and the Threema app. To prevent this from happening, please perform the following steps:

  • Summon the Task Manager (by pressing the menu button on your device)
  • Find Threema; Xiaomi: drag Threema downwards until the padlock icon appears
  • Tap the padlock icon (the padlock icon will then turn into a closed padlock)

Please note: When using a Xiaomi device, you need to perform these steps again after a restart.

Should the problem persist, please run WebRTC Diagnostics, and send in the result:

  • In Threema, open the main menu and navigate to Settings > About Threema > Troubleshooting > WebRTC Diagnostics, and tap Start
  • Wait until the test is completed, and tap “Copy to Clipboard”
  • Send the copied text along with a short description of the problem to the Threema ID *SUPPORT

We will then analyze the problem and get back to you as soon as we can.


Open the task manager, navigate to Threema, and tap the lock icon (which will close the lock).


If the iOS device is locked, the battery level is low, or Threema is in the background, Threema Web might be slower or less responsive. Connect your device to an external power source, and open the Threema app.

If re-establishing a connection to Threema Web fails, either push notifications aren't working properly or there is a problem in regard to Threema’s background activity. Please follow the troubleshooting instructions for Android or iOS.


URL actions allow to perform an action in Threema by tapping on a link. The following URL actions are available. (ABCDEFGH serves as placeholder for an arbitrary Threema ID.)

  • Add ID to contact list

    If the contact list does not contain the specified ID, the ID will be added to the contact list, and the contact details will be opened. If the contact list contains the specified ID, the respective chat will be opened.

  • Open chat

    Opens the chat with the specified ID. (If the contact list doesn’t contain the ID, the ID will be added to the contact list.)

  • Compose message

    Opens the chat with the specified ID and enters the provided text into the text field. (If the contact list doesn’t contain the ID, the ID will be added to the contact list.)

    Opens the contact picker. The provided text will be entered into the text field of the chat with the selected contact.

(The threema://-URL actions are still available. However, it is recommended to use the actions listed above whenever possible.)

To verify your phone number, simply tap the link in the message you have received.

Please note: If you have already entered the code manually, there’s no need to tap the link since your phone number has already been verified.

For security reasons, there is no way to recover lost PIN codes, passphrases, or lock codes. However, you can reset the app, and set it up again. Please note: Unless you have a backup, you will lose your Threema ID and all saved messages. (If you don’t remember your backup’s password, it cannot be recovered.)

Android: Delete the app data in Settings > Apps > Threema > Clear data.

iOS: Enter a wrong code ten times. A button will appear that allows you to reset the app data.

With Threema Gateway, Threema can be integrated into existing software applications. This allows companies and organizations to send, receive, and process Threema messages using their own software. Threema Gateway can be used for various purposes, the possibilities are virtually endless. Here are some real-world examples:

  • Userlike enables companies to communicate with customers and employees using various channels, including Threema.
  • Corona Radar, a service by Whappodo, allows Threema users to retrieve regional Corona stats right in the Threema app.
  • IncaMail, Swiss Post’s secure email service, uses Threema Gateway to forward encrypted emails. For example, payslips can be received not only as secure email but also as Threema message.
  • With a plugin, Threema can be used for two-factor authentication in the forum software xenForo.
  • Mercedes-Benz uses Threema Gateway for their messenger newsletter.
  • Whappodo, which also supports Threema, is a solution for customer care and broadcasting via instant messenger.
  • AMBER Alert Germany notifies the people via Threema about cases of missing children.

Besides the above-mentioned xenForo plugin, there are many other Open Source projects that use Threema Gateway, e.g., Grafana and Mattermost.

To learn more, please visit the Threema Gateway website.

The management of chats and media files depends on your operating system:


In the side menu, navigate to Settings > Media & Storage > Storage Management, where you can check the storage and choose between the following options:

  • Delete media and files that are older than the specified amount of time (1 week to 1 year)
  • Delete messages that are older than the specified amount of time (1 week to 1 year)

Please note: Messages are not deleted automatically but only when tapping the respective “Delete” button.

Selectively delete media files of specific chats: In a chat, select “Media Gallery” in the menu and use the drop-down menu to filter the listed files (all, images, videos, voice messages, other files). Tap and hold an item, and then tap on other items to add them to the selection (or tap the “Select all” button in the title bar to select all items). Finally, tap the trash-bin icon to delete the selected items.

To delete multiple chat messages at once, tap and hold one message, select the others you wish to delete, and then tap the trash bin in the top right corner.


In Settings > Storage Management, you get an overview of your device’s disk space and the space used by Threema. To free up space, you can choose between the following options:

  • Delete all media and files (of a certain age)
  • Delete all messages (of a certain age), including media and files

Please note: Messages are not deleted automatically but only when tapping the respective “Delete” button.

To delete all media files of a certain chat:

  • Open the chat, and tap on the title bar
  • Tap on “Media” in the bar that appeared below the title bar
  • Tap on “Edit”, select “Delete All”, and confirm

Threema Work is the secure communication platform for organizations. To learn more, please refer to the Threema Work website.

If some of your friends don’t use Threema yet, you can invite them as follows:

  • Android: Navigate to the contact list, tap on «Invite a Friend», and select the desired service. 
  • iOS: In Threema, navigate to «Settings > Invite a Friend», and choose the desired service.

Here’s how to verify (or add) the Threema support ID:

  • Android: In Threema, navigate to “Contacts”, tap on the “+” button, and select “Scan ID”, and scan the QR code below.
  • iOS: In Threema, navigate to My Profile, tap on the QR-code icon in the top right corner, and and scan the QR code below.

Note that in general, QR codes for ID verification should not be sent over the Internet but only scanned from the personal mobile phone of the respective person in order to ensure that there has been no manipulation by third parties.

You can order stickers, mugs, T-shirts and other Threema gear here:

Contact Our Support Team

To get technical assistance by the German-speaking Threema community, visit the unofficial Threema Forum (not affiliated with Threema GmbH).

If you couldn’t find an answer to your question in the FAQs above, please get in touch with our support team.

Contact support