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<!DOCTYPE html> <html lang="en"><head><title>Open Source – Transparency Matters – Threema</title><link rel="canonical" href="https://threema.ch/en/open-source"/> <link rel="stylesheet" href="https://static.threema.ch/fonts/labgrotesque.css"/> <meta name="viewport" content="width=device-width, initial-scale=1.0"/> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <meta name="description" content="The Threema apps are open source. 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class="nav-item" data-key="products"><a class="nav-link" href="/de/open-source" title="Deutsch">Deutsch</a></div><div class="nav-item active" data-key="products"><a class="nav-link" href="/en/open-source" title="English">English</a></div><div class="nav-item" data-key="products"><a class="nav-link" href="/fr/open-source" title="Français">Français</a></div><div class="nav-item" data-key="products"><a class="nav-link" href="/es/open-source" title="Español">Español</a></div></ul></div></div></header><main class="main" role="main"><div class="thr-section thr-top-section thr-top-section--withBox"> <div class="container-fluid"> <div class="row justify-content-center"> <div class="col-lg-12 col-md-10 col-12"> <h1 class="text-center thr-main-title">Open Source</h1> <div class="thr-bar-divider mx-auto"></div> </div> <div class="col-md-8 col-10"> <h4 class="text-center text-secondary-gray600 ">What’s better than trust? Transparency.</h4> </div> </div> </div> </div> <div class="thr-section thr-box-section thr-section--angleTopRight thr-section--angleBottomLeft"> <div class="container-fluid"> <div class="thr-box-section-content thr-box-section-content--big"> <div class="row justify-content-center"> <div class="col-10"> <p>Threema’s algorithms and design decisions are documented in the <a href="/press-files/2_documentation/cryptography_whitepaper.pdf">Cryptography Whitepaper</a>, and external experts are commissioned to conduct comprehensive <a href="/en/faq/code_audit">security audits</a> on a regular basis. However, it’s not necessary to believe our claims or to trust someone else’s assessment. To ensure full transparency, the Threema apps are open source.</p> <p>On this subsite, developers and security researchers who would like to take a look at Threema’s source can find information on how to download, build, and reproduce the apps’ code.</p> </div> </div> </div> </div> </div> <div class="thr-section thr-section--bgWhite pb-5" id="overview"> <div class="container-fluid"> <div class="row justify-content-center"> <div class="col-lg-10"> <div class="my-5"> <div class="thr-subNavigation"><a class="thr-subNavigation-item thr-btn" href="/en/open-source#overview">Overview</a><a class="thr-subNavigation-item" href="/en/open-source/reproducible-builds">Reproducible Builds</a><a class="thr-subNavigation-item" href="/en/open-source/contributions">Contributions</a><a class="thr-subNavigation-item" href="https://github.com/threema-ch">GitHub</a></div> </div> <div class="mb-5"> <h2 class="text-center thr-subtitle">Overview</h2> <div class="thr-bar-divider mx-auto"></div> </div> <div class="py-3"> <h3><a name="source"></a>Source Code and Documentation</h3> <div class="thr-bar-divider"></div> <h4>Mobile Apps</h4> <ul> <li><a href="https://github.com/threema-ch/threema-android">Threema for Android</a></li> <li><a href="https://github.com/threema-ch/threema-ios">Threema for iOS</a></li> </ul> <h4>Desktop App / Threema Web</h4> <ul> <li> <a href="https://github.com/threema-ch/threema-web-electron">Threema 1.x for desktop:</a> The app for macOS, Windows, and Linux </li> <li> <a href="https://github.com/threema-ch/threema-desktop/">Threema 2.0 for desktop (beta)</a>: The next-generation desktop app for macOS, Windows, and Linux </li> <li><a href="https://github.com/threema-ch/threema-web">Threema Web</a>: The Threema Web application </li> <li><a href="https://github.com/threema-ch/push-relay">Push Relay</a>: Push notifications for Threema Web </li> <li><a href="https://github.com/threema-ch/compose-area">Compose Area</a>: Library for a compose area with support for inline images </li> <li><a href="https://threema-ch.github.io/app-remote-protocol/">App Remote Protocol</a>: Documentation of the Threema Web protocol </li> </ul> <h3><a name="build-instructions"></a>Build Instructions</h3> <div class="thr-bar-divider"></div> <p>Build and test instructions can be found in the <code>README</code> files included in the source-code repositories.</p> <h3><a name="reproducible-builds"></a>Reproducible Builds</h3> <div class="thr-bar-divider"></div> <p>In order to verify that the published source code actually matches the source code the mobile apps in the stores were built with, we provide <a class="nw" href="https://reproducible-builds.org/">reproducible builds</a>.</p> <p>At the moment, reproducible builds are available for Threema’s Android app. Due to restrictions by Apple, it’s no easy task to offer reproducible builds for iOS, but we are currently evaluating possible ways to also support reproducible builds for this platform.</p> <p>For instructions on how to reproduce the published Android app build, please refer to the <a href="/en/open-source/reproducible-builds">Reproducible Builds page</a>.</p> <h3><a name="reports"></a>Bug Reports / Feature Requests / Security Issues</h3> <div class="thr-bar-divider"></div> <p>To report bugs or request new features, please <a href="/en/support">contact the Threema support team</a>.</p> <p>If you discover a security issue in Threema, please adhere to the coordinated vulnerability disclosure model.</p> <p>To be eligible for a bug bounty, please file a <a href="https://app.gobugfree.com/programs/threema" class="nw">report on GObugfree</a> (where all the details, including the bounty levels, are listed).</p> <p>If you’re not interested in the bug bounty program, you can contact us via Threema or by email; for contact details, see <a href="/en/contact">threema.ch/contact</a> (section “Security”). </p> <h3><a name="contributions"></a>Contributions</h3> <div class="thr-bar-divider"></div> <p>You can contribute to the Threema apps through pull requests on GitHub, after signing the <a href="/en/open-source/cla">Contributor License Agreement</a>. Please refer to the <a href="/en/open-source/contributions">Submitting Contributions</a> page for more information. (To translate the Threema app, please don’t create a pull requests; contact our <a href="/en/support-request">support</a> to get added as community translator on Crowdin.)</p> <h3><a name="license"></a>License</h3> <div class="thr-bar-divider"></div> <p>The Threema apps are subject to the <a href="https://www.gnu.org/licenses/agpl-3.0.en.html">GNU Affero General Public License version 3</a>. More details can be found in the source code repositories.</p> <p>Please note that even though they may be compiled and modified freely, the Threema apps are still paid apps. An anonymous license check prevents the creation of Threema IDs on self-compiled apps. If you would like to use a self-compiled app, please restore the backup of an existing Threema ID. You can create Threema IDs and backups thereof using the <a href="/en/download">purchased app</a>. <p>If you have questions about the use of self-compiled apps or the license in general, feel free to <a href="mailto:opensource@threema.ch">contact us</a>. We are publishing the source code in good faith, with transparency being the main goal. By having users pay for the development of the app, we can ensure that our goals sustainably align with the goals of our users: Great privacy and security, no ads, no collection of user data!</p> </div> </div> </div> </div> </div> </main> <footer class="border-top footer mb-4 pt-5"><div class="container-fluid container-fluid--xl"><div class="footer__row mb-3"><div class="footer__block"><span class="thr-ft-title">Products</span><a class="thr-ft-link" href="/en" title="Overview">Overview</a><a class="thr-ft-link active" href="/en/secure-messenger" title="Threema">Threema</a><a class="thr-ft-link" href="/en/work/business-messenger" title="Threema Work">Threema Work</a><a class="thr-ft-link" href="/en/broadcast" title="Threema Broadcast">Threema Broadcast</a><a class="thr-ft-link" href="/en/onprem" title="Threema OnPrem">Threema OnPrem</a><a class="thr-ft-link" href="/en/gateway" title="Threema Gateway">Threema Gateway</a></div><div><div class="footer__block"><span 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