There are numerous instant messengers around, and at first glance, they hardly differ. However, if you take a closer look, distinctive differences become apparent beneath the surface, especially as far as security and privacy protection are concerned. The following comparison shows how the most popular messengers stack up against one another.
Find out how the most popular chat apps stack up against one another.
The comparison was compiled to the best of our knowledge based on publicly available information (as of January 2021). Should you discover any errors, please let us know.
Threema compared to:
Both Signal and Threema were designed with security and privacy in mind. Signal enjoys an outstanding reputation among experts, and it’s certainly a solid solution in terms of security. As far as privacy is concerned, however, a striking drawback appears when compared to Threema.
Signal requires users to disclose personally identifiable information. Threema, on the other hand, can be used anonymously: Users don’t have to provide their phone number or email address. The fact that Signal, being a US-based IT service provider, is subject to the CLOUD Act only makes this privacy deficit worse.
Because Telegram already offered optional end-to-end encryption when this technology was not yet widespread, it’s sometimes wrongly labeled “secure” to this day. However, Telegram fundamentally differs from secure solutions like Threema since it’s essentially a cloud solution.
By default, Telegram permanently stores messages on its server, where they could, in theory, be read by the service provider at any time. Threema, on the other hand, rules out the possibility that anyone other than the intended recipient can read messages thanks to end-to-end encryption. After messages are delivered, they are immediately and irrevocably deleted from the Threema server.
However, its relaxed approach to security and privacy allows Telegram to offer some features that security-focused solutions like Threema are unable to provide without significant technical effort.
WhatsApp is the most popular instant messenger, and this is its biggest advantage. However, the weak privacy protection, which is a result of the service’s business model, is an even bigger disadvantage.
Facebook, the owner of WhatsApp, is financed by selling targeted advertisements. This business model requires as detailed user information as possible. Therefore, WhatsApp cannot be used without disclosing personally identifiable information, and user data is used by Facebook for marketing purposes.
Threema is financed by app sales. The service can be used without providing any personal data whatsoever, and the system is designed from the ground up to generate as little user data as technically possible.
Security and Privacy
Which messenger is the most secure? Which one offers the most comprehensive privacy protection?
Privacy by Design: No phone number or email address required
The service can be used anonymously.
End-to-end encryption of transmitted messages
Other than the intended recipient, no one (not even the service operator) can read regular chat messages.
Circumvention of end-to-end encryption is not possible
It’s not possible to circumvent the end-to-end encryption by means of unencrypted message copies on the device, there is no fingerprinting and no status feature on the server side, and received URLs are not opened automatically.
Service runs its own server
The service provider operates and runs all servers, and there are no cloud or hosting services (such as Amazon AWS or Google Cloud) involved.
No storage of chat messages on the server
Messages are immediately and irrevocably deleted from the server once they are delivered to the recipient.
No use of user data for advertising purposes
User data is not used for targeted advertising or for other marketing purposes.
No address-book access required
It’s not necessary to grant access to the address book in order to use the service.
Contact lists, groups, and user profiles are managed directly on the user devices, not on a central server.
The identity of contacts can be verified out of band, e.g., by scanning a QR code, and the verification is persistent.
The service complies with the European General Data Protection Regulation (GDPR).
The app’s source code is publicly accessible, and reproducible builds can be used to verify that it actually corresponds to the app available for download.
Latest security audit
When was the latest security audit conducted by external experts?
In terms of security and privacy protection, there’s no match for Threema. It’s the only service that can be used anonymously, i.e., without providing personally identifiable information (such as a phone number or email address). Signal is also designed with security and data protection in mind, but since it’s a US service, it is subject to the CLOUD Act, and it requires users to disclose personally identifiable information.
Which chat app provides the most useful features?
Text and voice messages
Voice and video calls
Communicate with users without revealing your personal information such as phone number or email address.
Conduct polls in group chats to collect the opinions of the group members.
Send messages to a chat bot to query information and interact with applications.
Mention users in group chats to trigger notifications.
Reference previous messages.
Send messages that are automatically deleted from the recipient's device after a specified period of time.
Deleting messages on recipient’s device8
Delete messages that have already been delivered to the recipient.
The listed services have a more or less similar range of features. Of course, they all support text and voice messages as well as voice and video calls. However, due to its security sacrifices, Telegram can offer the most features. Both Telegram and Threema allow users to remain anonymous to their chat partners.
Even though Signal focuses on security and privacy, the service supports “self-destructing” messages, which is a controversial feature as far as security is concerned.6
How does the application interact with additional devices?
Desktop app / web client
Chat from computer using web client or desktop app.
Use the same identity in parallel on multiple devices.
Use different identities on the same device.
Transfer basic user data between Android and iOS.
All services can be used on desktop computers. Being a cloud solution, Telegram also benefits form certain advantages in this category. And while WhatsApp scores badly in terms of portability, Signal and Threema are almost on par, which is about to change with the introduction of Threema’s multi-device solution.