Team Collaboration & Docs
Top 2 Self-Hosted Open-Source Alternatives to Slack (2026)
Slack costs Pro ($8.75/seat/mo) ($88/mo or $1,050/year for 10 seats). Switch to one of the verified open-source Docker replacements below.
★ 31.5k Stars • MIT / AGPL-3.0
1024MB RAM / 1.0 vCPU
Mattermost
Enterprise-grade open-source team messaging, playbooks, and voice calls
- ✓Slack-compatible webhooks & slash commands
- ✓Built-in voice calls & screen sharing
- ✓Unlimited searchable history forever
mattermost/mattermost-team-edition:release-10
TCO & Docker Compose →
★ 22.1k Stars • Apache-2.0
1536MB RAM / 2.0 vCPU
Zulip
Organized threaded team chat designed for deep async work and distributed engineering teams
- ✓Topic-based threading prevents chat chaos
- ✓100+ native integrations
- ✓Fast mobile & desktop apps
zulip/docker-zulip:latest
TCO & Docker Compose →