Best Open Source Alternatives to Slack

Omnichannel open-source customer and team chat hub built with Javascript.

vs Slack: a free, open-source option you fully control, licensed MIT.

Secure open-source developer collaboration and chat platform built for technical teams.

vs Slack: a free, open-source option you fully control, licensed AGPL-3.0.

Async-oriented team chat software offering structured email-like threaded messaging.

vs Slack: a free, open-source option you fully control, licensed Apache-2.0.

Reference homeserver implementation for secure, decentralized Matrix network messaging.

vs Slack: a free, open-source option you fully control, licensed Apache-2.0.

Open-source community server alternative to Discord built with Rust and TypeScript.

vs Slack: a free, open-source option you fully control, licensed AGPL-3.0.