Zulip

Zulip: Open Source Alternative to Slack and Rocket.Chat

Zulip is an open-source team chat platform whose defining feature is topic-based threading: every message belongs to both a channel and a topic, so long or asynchronous discussions stay organized instead of scrolling away. It's Apache-2.0 licensed and fully self-hostable, with a managed Zulip Cloud option for teams that don't want to run their own server.

Core features

• Topic-threaded channels — every message sits inside a named topic within a channel, so parallel conversations don't interleave the way they do in flat, channel-only chat.
• Full-text search — search across the entire message history, filterable by channel, topic, sender, and date.
• Bots and API — a documented REST API and bot framework for building integrations.
• Integrations — built-in connectors for common developer and business tools (CI, issue trackers, calendars, and more).
• Cross-platform apps — native desktop and mobile clients alongside the web app.
• Self-hosting or managed cloud — run it yourself for full control, or use Zulip Cloud; Zulip publishes free or discounted cloud plans for open-source projects, education, and non-profits.

Zulip vs Rocket.Chat and Slack

	Zulip	Rocket.Chat	Slack
Conversation model	Channels + topics (threaded)	Channels + threads	Channels + threads
Price	Free self-hosted; Zulip Cloud paid plans (discounts for OSS/nonprofit)	Free community edition; paid enterprise tiers	Free tier; paid per-seat plans
Hosting	Self-hosted or Zulip Cloud	Self-hosted or Rocket.Chat cloud	Cloud only, no self-hosting
License	Apache-2.0	MIT (community edition)	Proprietary
Built-in voice/video	No (via integrations)	Yes	Yes (huddles)

Use cases

• Distributed and async teams across time zones who need conversations to stay legible days later, not just in real time.
• Open-source projects with high message volume across many parallel discussions (this is Zulip's own origin use case).
• Teams frustrated by Slack channel noise who want a structure that doesn't rely on everyone reading everything as it happens.

Limitations

• The topic model has a real learning curve for teams used to flat, Slack-style channels — it takes deliberate habit-forming to use well.
• No built-in voice or video calling; you're relying on integrations (e.g. Zoom/Jitsi links) rather than a native call button.
• Self-hosting Zulip is a heavier operational commitment than a single-container app like Campfire — it's a multi-service Django/PostgreSQL/RabbitMQ stack.

Which one should you choose?

• Want organized, high-volume, asynchronous discussion? Zulip's topic model is built exactly for this.
• Want built-in voice/video without extra integrations? Rocket.Chat or Slack cover that natively.
• Don't want to operate a multi-service stack yourself? Zulip Cloud or Slack remove the ops burden; Campfire is lighter still if you do want to self-host.

FAQ

Is Zulip a free, open-source alternative to Slack?

Yes. Zulip is Apache-2.0 licensed and free to self-host, with no per-seat fees for the self-hosted version. A managed Zulip Cloud is also available, including free or discounted plans for open-source, education, and non-profit use.

How is Zulip different from Rocket.Chat or Mattermost?

Its topic-based threading model organizes conversations more granularly than the channel-only approach of Rocket.Chat and Mattermost, which suits asynchronous and high-volume teams especially well.

Does Zulip have voice or video calling?

Not natively — it relies on integrations with tools like Zoom or Jitsi rather than a built-in call feature.

What are the top open-source alternatives to Slack?

Browse more open-source alternatives to Slack, or explore the full Communication & Community category.

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Mise à jour par Maxime, le 25/07/2026.