Open source, self-hosted Slack-alternative.
Workplace messaging for web, PCs & phones with native apps. MIT-licensed. Hundreds of contributors. 10 languages. Secure, extendable, and scalable from teams to enterprise.
Ranked in these QuestionsQuestion Ranking
Pro Can be self-hosted
You don't need to rely on someone else's servers, you can host Mattermost on your own server.
Pro One-line Docker install
With Docker set up, you can install Mattermost with the following command:
docker run --name mattermost-dev -d --publish 8065:80 mattermost/platform
For other cases, installation instructions can be found here.
Con Poor Android application
Mattermost's Android application is thus far (2017-01-10) still just a poorly wrapped webview with the usual performance problems and a lack of offline functionality.