Good news! Threema for Windows Phone 8 is coming in autumn. No release date has been set yet but we'll keep you posted.

Threema uses true end-to-end encryption from the sender to the recipient based on established and renowned cryptography. An additional encryption layer providing Perfect Forward Secrecy (PFS) ensures that the meta data (information regarding who communicates with whom) cannot be intercepted during transport. The second fundamental difference between Threema and other mobile messengers is that Threema does not collect, mine or sell any data. You can use Threema anonymously, without providing a phone number. In summary:

• True end-to-end encryption
• Perfect Forward Secrecy (PFS) on data transport layer
• No data is collected, mined or sold
• Fully anonymous use possible
• Simple confirmation of trusted contacts with QR code
• Independent company, with no external financial interests
• Clear privacy policy
• Servers located in Switzerland

More info: Press-Info and Privacy Policy

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

There is a validation log feature in the app that can be used for independent verification of the end-to-end encryption. See here for details.