4 open source alternatives to Microsoft Teams
Video, chat, and collaboration bundled with Microsoft 365. Here are the open source projects real teams use instead — ranked by fit, with honest pros and cons for each.
What people don't love about Microsoft Teams
- Deeply tied to Microsoft ecosystem.
- Resource-heavy desktop client.
- Chat and meeting features sprawl across tabs.
Current Microsoft Teams pricing (for reference): Included in Microsoft 365 from $6.99/month; Teams Essentials from $4/user/month standalone.
Quick comparison
| Alternative | Best for | License | Self-host | Hosted cloud? |
|---|---|---|---|---|
|
Mattermost Slack-style open source team messaging. |
Enterprise teams needing Teams-like structure with compliance controls. | AGPL-3.0 / Apache-2.0 (modules) | ★★★☆☆ | Yes |
|
Element (Matrix) Decentralized messaging on the Matrix protocol. |
Federation plus end-to-end encryption for regulated industries. | Apache-2.0 | ★★★★☆ | Yes |
|
Rocket.Chat Open source team and community chat with video and voice. |
Large organizations with omnichannel and complex permissions. | MIT (community); proprietary modules available | ★★★☆☆ | Yes |
|
Zulip Threaded team chat with topics. |
Async-heavy teams that want topic-based threading. | Apache-2.0 | ★★★☆☆ | Yes |
1. Mattermost — Enterprise teams needing Teams-like structure with compliance controls.
Slack-style open source team messaging.
Strengths
- Familiar Slack-like UX.
- Strong self-hosting story and enterprise features.
- Good permission and compliance controls.
Weaknesses
- Some advanced features require paid tier.
- Mobile app performance is acceptable but not stellar.
- Larger install footprint than lightweight chats.
Mattermost homepage · Source on GitHub · Microsoft Teams vs Mattermost →
2. Element (Matrix) — Federation plus end-to-end encryption for regulated industries.
Decentralized messaging on the Matrix protocol.
Strengths
- Fully federated — you own your data.
- End-to-end encryption by default.
- Bridges to Slack, Discord, WhatsApp, etc.
Weaknesses
- Self-hosting Synapse or Conduit server is work.
- E2E encryption UX (device verification) can confuse users.
- Cross-signing and key backup setup is fiddly.
Element (Matrix) homepage · Source on GitHub · Microsoft Teams vs Element (Matrix) →
3. Rocket.Chat — Large organizations with omnichannel and complex permissions.
Open source team and community chat with video and voice.
Strengths
- Federation support (via Matrix bridge).
- {'Large feature set': 'channels, threads, omnichannel.'}
- Strong customization options.
Weaknesses
- Can feel heavy for small teams.
- Past performance issues on large deployments.
- Resource footprint is higher than competitors.
Rocket.Chat homepage · Source on GitHub · Microsoft Teams vs Rocket.Chat →
4. Zulip — Async-heavy teams that want topic-based threading.
Threaded team chat with topics.
Strengths
- Topic-based threading prevents channel noise.
- Great for async and open-source communities.
- Powerful search and history.
Weaknesses
- Topic model has a learning curve.
- Smaller ecosystem of third-party integrations.
- UI feels less polished than Slack.
Zulip homepage · Source on GitHub · Microsoft Teams vs Zulip →
Not what you're looking for?
Browse other tools in Team Communication, or check out open source projects by category on the full category index.
Recommended reading
Why your team probably can't ditch Slack yet (and what needs to change)
Mattermost and Rocket.Chat are excellent. So why do most teams who try to migrate away from Slack end up back on Slack? An honest look at the real blockers.
When self-hosting goes wrong: seven failure modes and how to avoid them
An honest retrospective on the ways self-hosted setups break — not in theory, but in practice — and the small habits that prevent most of them.
Will the open source project you depend on still exist in three years?
Bus factor, maintainer burnout, funding models, and the signals that separate OSS projects that survive from those that quietly decay.