Mattermost
Mattermost is a free, open-source messaging app for Android. Secure, self-hosted workplace messaging. It has 2,741 GitHub stars and is released under the Apache-2.0 license, and you can install it from F-Droid.
github.com/mattermost/mattermost-mobile (opens in a new tab)
Data as of from the GitHub API and the F-Droid index; description from the project's repository or F-Droid listing. Report an error
About Mattermost
Requires Mattermost Server v11.7.0+. Older servers may not be able to connect or have unexpected behavior. ------- Mattermost is secure workplace messaging from behind your firewall. - Discuss topics in private groups, one-to-one or team-wide - Easily share and view image files - Connect in-house systems with webhooks and Slack-compatible integrations To use this app, you need a URL for a Mattermost server. ------- Host your own server: Terms of Service: Contribute to the project:
Privacy and F-Droid
F-Droid builds Mattermost from its published source code and flags anti-features such as ads, tracking or reliance on non-free services.
No anti-features flagged on the latest F-Droid build.
Similar apps
More open-source messaging apps
QUIK SMS
quik-sms/quik
Open source replacement to the stock SMS app on Android.
Active · last commit Sep 27, 2026
Messaging & chatAndroid
Element X
element-hq/element-x-android
Sovereign. Seamless. On Matrix.
Active · last commit Oct 27, 2026
OfficialMessaging & chatAndroid
FluffyChat Matrix Messenger
krille-chan/fluffychat
The open-source, non-profit European alternative to big tech’s messaging and vid.
Active · last commit Oct 28, 2026
Messaging & chatAndroidiOSRocket.Chat
RocketChat/Rocket.Chat.ReactNative
The Secure CommsOS for mission-critical operations.
Active · last commit Oct 27, 2026
OfficialMessaging & chatAndroidiOS
Element Classic
element-hq/element-android
Previous generation Element.
Active · last commit Sep 25, 2026
OfficialMessaging & chatAndroidConduit
cogwheel0/conduit
Native iOS and Android client for Open WebUI, direct OpenAI-compatible, Ollama, and Hermes agents.
Active · last commit Oct 26, 2026
Messaging & chatAndroidiOS
Is Mattermost free and open source?
Yes. Mattermost's source code is public on GitHub under the Apache-2.0 license, which is OSI-approved or FSF-free. F-Droid, which builds it from source, flags no anti-features such as ads or tracking on its latest build.
How do I install Mattermost?
You can install Mattermost from F-Droid (package com.mattermost.rnbeta); the links are on this page. Its GitHub repository also publishes releases (latest: v2.45.1).
Is Mattermost still maintained?
The repository's most recent commit was on Oct 27, 2026. Its F-Droid listing was last updated on Oct 16, 2026. appsgit only lists apps whose repository had a commit in the last six months.