Mattermost

Open SourceOtherSelf-hostable

Secure, self-hostable messaging platform for technical and security-conscious teams, with channels, threads, integrations and playbooks — the most established open alternative to Slack.

Open source alternative to

Slack

Visit Mattermost View source

About Mattermost

Mattermost has spent a decade becoming the default choice for security-conscious and regulated teams that need Slack-style messaging but can't put internal communications on someone else's servers. Channels, threads and incident playbooks cover the same daily workflow Slack does.

It's genuinely built for on-prem and self-hosted deployment, with deep DevOps and CI/CD integrations that make it a natural fit for engineering-heavy organizations that need full data ownership.

Key features

Channels & threads — The same channel- and thread-based messaging model teams already know from Slack.
Enterprise-grade security — Compliance, audit and data-residency features built for regulated industries.
Incident playbooks — Structured, repeatable playbooks for running incident response inside chat.
Deep DevOps integrations — Native integrations with CI/CD and infrastructure tooling most engineering teams already run.

The honest read

What we like

Enterprise-grade security and compliance features
Mature and battle-tested at scale
Strong DevOps and CI/CD integrations
Full data ownership when self-hosted
Long, stable track record

Worth knowing

Self-hosting requires real infrastructure investment
UI feels more utilitarian than Slack's
Some advanced features are Enterprise-tier only
Mobile push notifications need extra setup when self-hosted

FAQ

Is Mattermost free to use?

Yes — Mattermost's core is free and open source, with paid Enterprise tiers for advanced compliance and support features.

Can I self-host Mattermost?

Yes — Mattermost is built for self-hosting and on-prem deployment, with an official Docker setup.

How is Mattermost different from Slack?

Mattermost is open source and self-hostable with strong compliance features for regulated industries, while Slack is a closed-source, cloud-only SaaS product.

Does Mattermost support incident response?

Yes — Mattermost includes structured incident playbooks for running response processes directly inside chat.