The Threema Web application.
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Threema Web

Build status License

Threema Web is a web client for Threema, a privacy-focussed end-to-end encrypted mobile messenger hosted and developed in Switzerland. With Threema Web, you can use Threema on your Desktop without compromising security.


Threema Web establishes a connection between Desktop and mobile device using WebRTC (Android) or encrypted WebSockets (iOS). Signaling and data is end-to-end encrypted with SaltyRTC.

For more information, see the Threema Cryptography Whitepaper.

Bug Reports and Feature Requests

If you find a bug in Threema Web or want to request a new feature, feel free to open an issue on GitHub. Please make sure that your bug report or feature request hasn't already been filed by using the search function.

Express your personal opinion regarding priority by reacting with 👍 in a particular issue, such as this one. We will factor this in when scheduling what to do next.


If you want to help translating Threema Web to your language, plese check out!


Threema Web is written using TypeScript and AngularJS 1. Dependencies are managed with npm. You currently need Node.js 8 or later to build Threema Web. (Note that Node.js is only a build dependency, the result is plain old client-side JavaScript.)

Install development dependencies:

npm install

Run the dev server:

npm run devserver

Then open the URL in your browser:

firefox http://localhost:9966

(Note that this setup should not be used in production. To run Threema Web on a server, please follow the instructions at docs/


To run unit tests:

npm run build && npm run build:unittests
firefox tests/testsuite.html

To run UI tests:

npm run test:ui <browser>

For example:

npm run test:ui firefox
npm run test:ui chrome

You can also filter the test cases:

npm run test:ui firefox emoji

To run linting checks:

npm run lint

You can also install a pre-push hook to do the linting:

echo -e '#!/bin/sh\nnpm run lint' > .git/hooks/pre-push
chmod +x .git/hooks/pre-push


The configuration of Threema Web can be tweaked in src/config.ts:


  • SELF_HOSTED: Set this to true if this instance of Threema Web isn't being hosted on
  • PREV_PROTOCOL_LAST_VERSION: When the Threema Web protocol version changes, this can be set to the last version of Threema Web that supported the previous protocol version. If set to something different than null, a message will be shown to the user if reconnecting fails.


  • SALTYRTC_HOST: Set this to the hostname of the SaltyRTC server that you want to use. If set to null, the hostname will be constructed based on the SALTYRTC_HOST_PREFIX and the SALTYRTC_HOST_SUFFIX values.
  • SALTYRTC_PORT: The port of the SaltyRTC server to be used.
  • SALTYRTC_SERVER_KEY: The public permanent key of the SaltyRTC server. Set this value to null if your server does not provide a public permanent key, or if you don't want to verify it.


  • ICE_SERVERS: Configuration object for the WebRTC STUN and ICE servers.


  • PUSH_URL: The server URL used to deliver push notifications to the app.

Self Hosting

For instructions on how to host your own version of Threema Web, please refer to docs/


Contributions to Threema Web are welcome! Please open a pull request with your proposed changes.


Every Threema Web release will be tagged. The git tags are cryptographically signed using the following PGP key:

pub   rsa4096 2016-09-06 [SC] [expires: 2026-09-04]
      E7AD D991 4E26 0E8B 35DF  B506 65FD E935 573A CDA6
uid           Threema Signing Key <>

If you discover a security issue in the Threema Web, please follow responsible disclosure and report it directly to instead of opening an issue on Github.

pub   rsa4096 2017-02-08 [SC] [expires: 2022-02-07]
      677E 0E97 1669 53B3 2620  D95C 71B9 C6BA C55A 9855
uid           Threema Security <>

You can find both public keys and their proofs on keybase. The security reporting key can also be found at


Threema Web license:

Threema Web.

Copyright © 2016-2018 Threema GmbH (

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <>.

For third party library licenses, see LICENSE-3RD-PARTY.txt.