Zulip vs Mattermost: Team Chat Compared
Quick Verdict
Mattermost is the better choice if you want a Slack replacement that your team can adopt without retraining. Zulip is better for teams that struggle with message overload — its topic-based threading model is genuinely superior for async communication and keeping conversations findable. Mattermost is simpler to deploy and run. Zulip demands more resources but rewards you with better organization.
Overview
Both Zulip and Mattermost are self-hosted team chat platforms designed to replace Slack and Microsoft Teams. Both offer channels, direct messages, file sharing, search, integrations, and mobile apps. The fundamental difference is how conversations are structured.
Mattermost follows the Slack model: messages flow chronologically in channels. Threads exist but are secondary — the main channel view dominates. This is familiar to anyone who has used Slack, Teams, or Discord. The Team Edition is MIT-licensed and free to self-host.
Zulip introduces a topic-based threading model where every message within a channel belongs to a named topic. Think of it as channels with mandatory subject lines. This makes it possible to follow multiple conversations in the same channel without confusion. Zulip is Apache 2.0 licensed with no paid-only features for self-hosted deployments.
Feature Comparison
| Feature | Zulip | Mattermost |
|---|---|---|
| Conversation model | Topic-based threads | Chronological (Slack-style) |
| License | Apache 2.0 | MIT + AGPL (Team Edition) |
| Paid features locked | None (all features available) | Playbooks, advanced compliance in Enterprise |
| Markdown support | Full with LaTeX | Full |
| Code blocks | Syntax highlighting | Syntax highlighting |
| File sharing | Yes | Yes |
| Search | Full-text with topic filtering | Full-text |
| Integrations | 150+ via webhooks and bots | 800+ plugins and integrations |
| Video/audio calls | Jitsi, BigBlueButton, Zoom integrations | Built-in Calls plugin (WebRTC) |
| Mobile apps | iOS, Android (open source) | iOS, Android (open source) |
| Desktop apps | Electron (Windows, macOS, Linux) | Electron (Windows, macOS, Linux) |
| Email notifications | Threaded email digests | Standard notifications |
| Guest access | Yes | Yes (Enterprise only) |
| LDAP/AD/SAML | Yes | Yes (some Enterprise only) |
| Read receipts | No | Yes |
| Message reactions | Yes | Yes |
| Custom emoji | Yes | Yes |
| Data export | Full | Full |
| API | REST + real-time events | REST + WebSocket |
Setup Complexity
Mattermost is significantly simpler to deploy. The Docker Compose stack has two services (Mattermost + PostgreSQL), requires minimal configuration, and starts with a single docker compose up -d. The first admin account is created through the web UI.
Zulip is more complex. The stack requires five services: Zulip, PostgreSQL (custom image with FTS extensions), Memcached, RabbitMQ, and Redis. Configuration uses a two-file approach (compose.yaml + compose.override.yaml) with Docker secrets for passwords. Initial setup requires editing environment variables before starting. Zulip also requires at least 2GB RAM with swap — tight deployments fail.
| Setup Aspect | Zulip | Mattermost |
|---|---|---|
| Services required | 5 (app, PostgreSQL, Memcached, RabbitMQ, Redis) | 2 (app, PostgreSQL) |
| Config files | 2 (compose.yaml + override) | 1 (docker-compose.yml) |
| First-run complexity | Edit env vars, then docker compose up | docker compose up, then web wizard |
| Time to working install | 15-30 minutes | 5-10 minutes |
| Docker rootless | Not supported | Supported |
Performance and Resource Usage
| Metric | Zulip | Mattermost |
|---|---|---|
| Minimum RAM | 2 GB + 2 GB swap | 4 GB |
| Recommended RAM | 4 GB | 4-8 GB |
| Idle RAM (all services) | ~800 MB - 1.2 GB | ~400-600 MB |
| Disk (application) | ~2 GB | ~500 MB |
| CPU (idle) | Low | Low |
| Scales to | Thousands of users | Thousands of users |
Mattermost uses less memory overall because it has fewer dependent services. Zulip’s PostgreSQL, Memcached, RabbitMQ, and Redis all consume RAM even at idle. On a 2GB server, Zulip will be tight — Mattermost will be comfortable.
The Threading Model Difference
This is the core decision point. Try both if you can, because the right choice depends on how your team communicates.
Mattermost (Slack model): Messages appear in chronological order in channels. Threads are optional — you can reply in-thread or in the main channel view. This is intuitive for most people because it mirrors Slack, Teams, and Discord. The downside: busy channels become impossible to follow. Important messages get buried. You scroll up, lose context, and miss things.
Zulip (topic model): Every message belongs to a named topic within a channel (called a “stream”). When you open a stream, you see topics listed — not a flat message list. You click into a topic to see its conversation. This means ten conversations can happen in the same channel without interfering with each other. The downside: it requires discipline. Every message needs a topic name, and users used to Slack find this friction annoying at first.
For async teams (different time zones, remote-first), Zulip’s model is objectively better at keeping conversations organized and findable. For real-time teams that mostly chat synchronously, Mattermost’s familiar model works fine.
Community and Support
| Aspect | Zulip | Mattermost |
|---|---|---|
| GitHub Stars | ~22,000 | ~30,000 |
| Release cadence | Monthly | Monthly |
| Community chat | Zulip Cloud (dogfooding) | Mattermost Community |
| Documentation | Excellent | Excellent |
| Commercial support | Zulip Cloud plans | Mattermost Enterprise |
| Notable users | Rust, LLVM, Lean, Python | Samsung, NASA, US Air Force |
Both have strong communities and professional backing. Zulip is popular with open-source projects and academic institutions — communities that value organized, asynchronous discussion. Mattermost is more common in enterprises that want a direct Slack replacement.
Use Cases
Choose Zulip If…
- Your team operates across time zones and needs async-friendly communication
- Channel noise is a problem — important messages get buried in your current tool
- You value conversation organization over familiar UX
- You want all features available without an Enterprise license
- Your team is willing to learn a new conversation model
- You run an open-source project or academic group
Choose Mattermost If…
- Your team is used to Slack and you want minimal retraining
- You need built-in video/audio calls (WebRTC, no external service)
- You want a simpler deployment (2 services vs 5)
- You need a large plugin/integration ecosystem
- Guest access without an Enterprise license is not required
- You prefer a lighter resource footprint
Final Verdict
For most teams replacing Slack, Mattermost is the safer choice. It is familiar, simpler to deploy, lighter on resources, and has a larger integration ecosystem. Your team will adopt it without friction because it looks and works like Slack.
Zulip is the better product for teams that take the time to learn it. The topic-based threading model solves Slack’s biggest problem — conversation chaos in busy channels. If your team communicates asynchronously across time zones, Zulip will save you from the “I missed that message” problem that plagues chronological chat. The tradeoff is a steeper learning curve and a heavier deployment.
If your team has complained about message overload in Slack, try Zulip. If they just want Slack without the subscription fee, use Mattermost.
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