Mattermost vs Zulip: which one to choose in 2026?
Both are open source alternatives to Slack. We compare license, tech stack and features to help you decide which fits your team best.
| Mattermost | Zulip | |
|---|---|---|
| Category | Productivity | Productivity |
| License | MIT | Apache-2.0 |
| GitHub stars | 30k | 21k |
| Tech stack | Go, React, PostgreSQL | Python, Django, PostgreSQL |
| Replaces | Slack, Microsoft Teams | Slack |
Mattermost has more GitHub stars, which usually indicates a larger community (not necessarily that it's the best option for your use case).
Mattermost
Security-focused team chat and collaboration, an alt. to Slack.
Pros
- Widely used in regulated and government environments
Things to consider
- The Team edition has fewer features than Enterprise
Zulip
Team chat organized by threads, an alternative to Slack.
Pros
- Much less noise than Slack in very active channels
Things to consider
- The topic-thread model has a learning curve
Key features
Mattermost
- Playbooks for incident management
- Native CI/CD integrations
- Configurable compliance and retention
Zulip
- Topic threads within each channel
- Powerful search across the whole history
- Native cross-platform apps