Our verdict: Mattermost suits technical teams that want Slack-style channels on a server they control. The desktop app is free and open source, but it is only a client: someone has to run a Mattermost server, and the free editions are meant for small teams.
About Mattermost
Mattermost is a self-hosted chat platform for teams, built by Mattermost, Inc. The Windows desktop app is open source under the Apache License 2.0 and connects to one or more Mattermost servers in tabs.
There are two free server options. Team Edition is MIT-licensed open source for small teams and personal use under 250 users without single sign-on. Entry is the free mode of the commercial Enterprise Edition, best for fewer than 50 users, with limits such as 10,000 viewable channel messages. Paid plans add support, compliance and scaling.
What it does well
- Channels and threads. Organise conversations in public and private channels with threaded replies.
- Multiple servers. Connect the desktop app to several Mattermost servers at once.
- Self-hosting. Keep all messages and files on your own server.
- Integrations. Webhooks, bots, slash commands and plugins for tools such as GitHub and Jira.
- Calls and screen sharing. Group audio calls with screen sharing on self-hosted servers.
Who it is for
Good fit
Developer and IT teams that want a self-hosted Slack alternative.
Look elsewhere
People who just want a free chat app without running or joining a server.
Pros and cons
Pros
- Desktop app and Team Edition are open source
- Data stays on your own server
- Many integrations for developer tools
- Several servers in one app
Cons
- Needs a Mattermost server to connect to
- Free Entry edition limits viewable message history to 10,000 messages
- Team Edition has no single sign-on
How to install Mattermost
Download the 64-bit MSI and run it. On first launch enter the URL of your team's Mattermost server and sign in. Add more servers later from the server menu.
Questions about Mattermost
Is Mattermost free?
Yes. The desktop app is free and open source, and both Team Edition and the Entry mode of the server are free. Paid plans add support and enterprise features.
Do I need a server for Mattermost?
Yes. The Windows app is a client; you connect it to a Mattermost server run by you or your organization.
