What is the difference between Slack and Zulip?

Slack is best for Teams that need organized, searchable communication, while Zulip is best for Open-source communities and teams wanting threaded messaging. Slack starts at $7.25/user/mo and Zulip starts at Free.

Is Slack or Zulip cheaper?

Slack starts at $7.25/user/mo with a free tier. Zulip starts at Free and is free.

Is there a free alternative to Zulip?

Both Slack and Zulip offer free tiers.

Slack vs Zulip

Slack is team messaging platform with channels, threads, and integrations for workplace communication, while Zulip is open-source team chat with a unique topic-based threading model for organized conversations. The biggest difference up front: Zulip is free, while Slack starts at $7.25/user/mo. Slack is built for teams that need organized, searchable communication, whereas Zulip targets open-source communities and teams wanting threaded messaging.

At a glance

	Slack	Zulip
Best for	Teams that need organized, searchable communication	Open-source communities and teams wanting threaded messaging
Starting price	$7.25/user/mo	Free
Free tier	✓	✓
Open source	—	✓
Free tier available	✓	✓
Open source	—	✓
Channels	✓	—
File Sharing	✓	—
Huddles	✓	—
Integrations	✓	—
Markdown	—	✓
Open Source	—	✓
Self-Hosted	—	✓
Threads	✓	—
Topic Threading	—	✓

Slack

Strengths

Massive integration ecosystem with 2,400+ apps
Excellent search across all messages and files
Familiar interface that most people already know
Strong API for custom bots and workflows

Weaknesses

Expensive at scale — costs add up fast with large teams
Can become noisy and distracting with many channels
Free tier limits message history to 90 days
Desktop app is resource-heavy

Try Slack → Full review

Zulip

Strengths

Open source and transparent
Topic-based threading keeps conversations organized by subject, not just time
Fully open-source — you can self-host, audit the code, and avoid vendor lock-in
The core product is free with no paywalled essentials

Weaknesses

May lack some advanced features
Self-hosting is free but requires server maintenance and DevOps knowledge
Self-hosting requires Linux admin skills and ongoing server maintenance
Notification overload is a real problem as the number of channels grows

Try Zulip → Full review

The bottom line

Pricing: Zulip is completely free, which makes it the obvious pick if budget is the top concern. Slack starts at $7.25/user/mo, but Free for small teams, 90-day history. That cost buys you a more polished or feature-rich experience, so it comes down to whether the extras justify the spend.

Feature gaps: Slack offers Channels, File Sharing and Huddles that Zulip lacks. Zulip brings Markdown, Open Source and Self-Hosted that Slack does not have.

Team fit: Both tools target any size teams, so the decision hinges on features and workflow fit rather than scale.

Open source: Zulip is open source, meaning you can self-host, audit the code, and avoid vendor lock-in. Slack is proprietary — you are trusting the vendor with your data and uptime.

Where each tool shines: Slack's biggest strengths are: massive integration ecosystem with 2,400+ apps. excellent search across all messages and files. Zulip's biggest strengths are: open source and transparent. topic-based threading keeps conversations organized by subject, not just time.

Watch out for: With Slack, users commonly note that expensive at scale — costs add up fast with large teams. With Zulip, the main complaint is that may lack some advanced features.

Choose Slack if...

Your profile matches its sweet spot: teams that need organized, searchable communication
You specifically need Channels and File Sharing
You care about excellent search across all messages and files
The free tier works for you: free for small teams, 90-day history

Choose Zulip if...

You need a tool built for open-source communities and teams wanting threaded messaging
Budget is a hard constraint — Zulip is free, Slack is not
You need self-hosting, data sovereignty, or the ability to audit source code
You specifically need Markdown and Open Source
You care about topic-based threading keeps conversations organized by subject, not just time