Mattermost
By Mattermost, Inc.
Mattermost is an open-source, self-hosted team messaging platform built as a Slack-style alternative for organizations that need to keep collaboration data on their own infrastructure.
Definition
Mattermost is an open-source, self-hosted team messaging platform built as a Slack-style alternative for organizations that need to keep collaboration data on their own infrastructure.
Overview
Mattermost launched in the mid-2010s specifically to give developer teams and enterprises a self-hostable alternative to hosted chat platforms like Slack. It's written in Go with a React-based web client, and both an open-source edition and a commercially licensed enterprise edition are available. Functionally, Mattermost provides channels, direct messages, threads, file sharing, and searchable message history, along with an extensive integration and webhook system for connecting to tools like GitHub and Jenkins. Because it's self-hosted, organizations run it on their own servers or Kubernetes clusters, giving them full control over data residency, retention, and compliance. Mattermost is particularly popular with government agencies, regulated industries, and engineering-heavy organizations that need chat data to stay inside their own network boundary, as well as open-source and DevOps teams that want deep integration with their existing CI/CD and incident-response tooling.
Key Features
- Fully self-hostable, open-source core available under an open license
- Channels, threads, direct messages, and searchable history similar to Slack
- Extensive webhook, slash-command, and integration framework
- Playbooks feature for structured incident response and workflow automation
- Deployable via Docker or Kubernetes for on-premises or private-cloud hosting
- Enterprise edition adding SSO, compliance, and advanced admin controls
- Mobile and desktop clients alongside the web application