Stacks / Support
Mattermost / Rocket.Chat
Team chat and calls you host. Mattermost and Rocket.Chat replace Microsoft Teams without the Microsoft 365 seat.
The problem
Microsoft Teams is bundled into Business Basic at $7/user/month paid yearly — until you needed only chat and paid for the suite. Mattermost is the open-source collaboration server; Rocket.Chat is already a c17 stack (Slack). Either one is a Teams off-ramp.
Replaces
Microsoft Teams
Estimated SaaS saved
$2,100
per year, small team, before lock-in
Start on RailwayPlaceholder: Mattermost (or reuse the Rocket.Chat stack) + Postgres. Persist data on a volume. Set SiteURL. Slack's /replace/slack page stays on Rocket.Chat alone.
The stack
- Mattermost
Open-source team chat, playbooks, and calls
- Rocket.Chat
Open-source workspace chat already in the catalog
Cost table
| You stop paying | Typical / year | Self-host instead |
|---|---|---|
| Microsoft 365 Business Basic (10 seats) | $840 | Mattermost or Rocket.Chat |
| Teams as the only reason for the suite | $2,100 | Same box; drop the M365 seat |
Agent setup prompt
Replace Microsoft Teams with Mattermost (preferred) or Rocket.Chat. - Postgres + a volume for files. SiteURL / ROOT_URL = the Railway public domain. - Create the first team, turn off public signup, document how to import a Teams export (or rebuild the channels that matter). - Write AGENT_PROMPT.md and a cost table vs Microsoft 365 Business Basic seats.
Also as markdown: /stacks/mattermost-teams.md
FAQ
- Why not the Slack page?
- /replace/slack is Rocket.Chat only. Teams is Mattermost first, Rocket.Chat second — same chat job, different vendor you are leaving.