We've just launched our brand new “Threema Gateway” product. It allows you to encrypt, send, receive and decrypt messages directly from your own application. The code for integrating a Threema backend into your own software environment is available in PHP, Java and Python and released with an Open Source license.
This new pre-paid service is more feature-rich, versatile and cheaper than traditional SMS gateways. It offers the highest possible security you've come to expect from Threema thanks to its reliable end-to-end encryption based on the well reputed NaCl cryptography library. All IDs used for messages sent via “Threema Gateway” start with an asterisk (*) and consist of 8 characters in total. You're free to choose your own Threema ID. Example: *THREEMA https://gateway.threema.ch