Replace Slack with self-hosted team messaging in 2026. Compare Mattermost, Rocket.Chat, and Element (Matrix) — unlimited message history, zero per-user pricing, full data ownership. Slack charges $7.25-$12.50/user/month; self-hosted saves thousands at scale.
Slack charges $7.25-$12.50 per user/month and limits message history to 90 days on free plans. Self-hosted alternatives offer unlimited message history, no per-user costs, and full data ownership. Mattermost is the most Slack-like experience with channels, threads, and integrations. Rocket.Chat adds video calls and omnichannel support. Element uses the decentralized Matrix protocol for maximum privacy.
Mattermost is the most straightforward with a Docker-based setup and Slack-compatible keyboard shortcuts and interface. One command: docker run -d -p 8065:8065 mattermost/mattermost-preview.
Yes. Mattermost has a built-in Slack import tool that migrates channels, users, and message history. Rocket.Chat also supports importing from Slack exports.
Slack Pro costs $7.25/user/month ($87/year). For a 50-person team, that is $4,350/year. Self-hosting Mattermost costs only the server (typically $20-$50/month), saving $3,750+/year.