Open-source alternatives to Slack
3 open-source and self-hostable projects you can use instead of Slack, with license, free-edition limits and setup checked against official sources.
- Rocket.ChatAlternative to Slack, Microsoft Teams
A self-hostable team communications platform with chat, channels, and omnichannel customer messaging.
MITSelf-hostedCloud46kGitHub starsSome features paywalled - MattermostAlternative to Slack
A self-hostable team chat platform with channels, threads and integrations, popular for secure and technical teams.
AGPL-3.0Self-hostedCloud39kGitHub starsSome features paywalled - ZulipAlternative to Slack
A self-hostable team chat app that organizes every conversation into topics inside channels.
Apache-2.0Self-hostedCloud26kGitHub starsNot yet assessed
- Rocket.Chat — Rocket.Chat is a team chat platform you can deploy on your own infrastructure, including air-gapped networks.
- Mattermost — Mattermost is a self-hostable team chat platform with channels, threads and integrations, offered as an alternative to Slack.
- Zulip — Zulip is an open-source team chat you can run on your own server, with topic-based threading in place of Slack's channel-and-thread model.