Home / Team Communication / Mattermost

Mattermost — open source alternative

Slack-style open source team messaging.

Strengths

Familiar Slack-like UX.
Strong self-hosting story and enterprise features.
Good permission and compliance controls.

Weaknesses

Some advanced features require paid tier.
Mobile app performance is acceptable but not stellar.
Larger install footprint than lightweight chats.

License: AGPL-3.0 / Apache-2.0 (modules) Self-host difficulty: 3/5 Hosted cloud optionDesktop: Windows, macOS, LinuxMobile: iOS, Android

Official site · Source on GitHub

Mattermost is used as an alternative to

Slack

Team messaging with channels, threads, and integrations.

See all alternatives →

Discord

Voice, video, and text chat — popular with gamers and communities.

See all alternatives →

Microsoft Teams

Video, chat, and collaboration bundled with Microsoft 365.

See all alternatives →

More open source in this category

Discover other projects tagged Team Communication on the category page.

Other open source projects in Team Communication

Rocket.Chat

Open source team and community chat with video and voice.

License: MIT (community); proprietary modules available

Zulip

Threaded team chat with topics.

License: Apache-2.0

Element (Matrix)

Decentralized messaging on the Matrix protocol.

License: Apache-2.0

Recommended reading

Why your team probably can't ditch Slack yet (and what needs to change)

Mattermost and Rocket.Chat are excellent. So why do most teams who try to migrate away from Slack end up back on Slack? An honest look at the real blockers.

When self-hosting goes wrong: seven failure modes and how to avoid them

An honest retrospective on the ways self-hosted setups break — not in theory, but in practice — and the small habits that prevent most of them.

Will the open source project you depend on still exist in three years?

Bus factor, maintainer burnout, funding models, and the signals that separate OSS projects that survive from those that quietly decay.