Mattermost
The open source team chat for organisations that cannot put it in Slack
Alternative toSlackMicrosoft Teams
Mattermost is team chat with channels, threads, direct messages and calls, the role Slack and Microsoft Teams play elsewhere. Its source is under AGPL-3.0 and Apache-2.0, it is built to be self hosted, and its company sells enterprise editions on top.
Best for when
- your organisation cannot keep internal chat on a third party cloud
- you need team chat that works on a private or air gapped network
- you want Slack style webhooks and bots against your own server
Watch out for
- single sign on, compliance and clustering features are in paid editions
- the free edition's limits have changed between versions, so check them before you rely on it
- mobile push notifications and upgrades are yours to run and keep working
Slack's shape, on your own servers
If you have used Slack you already know Mattermost: channels, threads, mentions, file sharing, search, bots and webhooks, with desktop and mobile apps. It also includes playbooks for repeatable checklists such as incident response, and boards for simple task tracking.
Its real audience is organisations that cannot send internal conversations to a third party cloud, such as government, defence, healthcare or companies with strict data rules. It runs as a Go server with PostgreSQL, and can work in air gapped networks.
What the free edition does not give you
The free self hosted edition covers chat well, but many features organisations want, such as single sign on with SAML, advanced compliance exports, high availability clustering and some admin controls, are in paid editions. The limits of the free edition have also changed in recent versions, so read the current comparison before you commit.
Compared with Slack, the integration catalogue is smaller and you run the server, the database, file storage, push notifications for mobile and the upgrades. Moving from Slack is possible with an import tool, but expect some message formatting, attachments or app integrations not to come across cleanly.
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