What is the difference between Mattermost and Lark?

Mattermost is best for Teams that need self-hosted, privacy-first messaging, while Lark is best for Teams wanting an all-in-one collaboration suite. Mattermost starts at Free (self-hosted) and Lark starts at Free.

Is Mattermost or Lark cheaper?

Mattermost starts at Free (self-hosted) and is free. Lark starts at Free with a free tier.

Is there a free alternative to Lark?

Both Mattermost and Lark offer free tiers.

Mattermost vs Lark

Mattermost is open-source, self-hosted team messaging platform for organizations that need data sovereignty, while Lark is integrated workspace combining messaging, video, docs, and project management from ByteDance. Mattermost is open source and can be self-hosted, giving you full control over your data. Mattermost is built for teams that need self-hosted, privacy-first messaging, whereas Lark targets teams wanting an all-in-one collaboration suite.

At a glance

	Mattermost	Lark
Best for	Teams that need self-hosted, privacy-first messaging	Teams wanting an all-in-one collaboration suite
Starting price	Free (self-hosted)	Free
Free tier	✓	✓
Open source	✓	—
Free tier available	✓	✓
Open source	✓	—
Calendar	—	✓
Channels	✓	—
Compliance	✓	—
Docs	—	✓
Integrations	✓	—
Messenger	—	✓
OKRs	—	✓
Playbooks	✓	—
Self-Hosted	✓	—
Video	—	✓

Mattermost

Strengths

Self-hosted — full control over your data
Open source with active community
Slack-compatible interface, easy migration
Strong compliance and security features

Weaknesses

Requires server management if self-hosting
Smaller integration ecosystem than Slack
Cloud-hosted version is more expensive than Slack
Mobile apps lag behind Slack and Teams in polish

Try Mattermost → Full review

Lark

Strengths

Includes Messenger as a core feature, purpose-built for team communication workflows
Includes Video as a core feature, purpose-built for team communication workflows
Free for up to 50 users — generous enough for most small teams to get real work done
Includes docs alongside the core feature set — fewer separate tools needed

Weaknesses

Free plan exists but key features are locked behind the paid upgrade
Feature-rich interface takes time to learn — not the simplest option for quick adoption
Notification overload is a real problem as the number of channels grows
Mobile experience lags behind the desktop version in features and polish

Try Lark → Full review

The bottom line

Pricing: Both Mattermost and Lark are free. You can try both without spending a dollar.

Feature gaps: Mattermost offers Channels, Compliance and Integrations that Lark lacks. Lark brings Calendar, Docs and Messenger that Mattermost does not have.

Team fit: Mattermost is geared toward mid-size teams teams, while Lark is aimed at any size teams. Pick the one that matches where your team is today and where it is headed — migrating tools later is always painful.

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

Where each tool shines: Mattermost's biggest strengths are: self-hosted — full control over your data. open source with active community. Lark's biggest strengths are: includes messenger as a core feature, purpose-built for team communication workflows. includes video as a core feature, purpose-built for team communication workflows.

Watch out for: With Mattermost, users commonly note that requires server management if self-hosting. With Lark, the main complaint is that free plan exists but key features are locked behind the paid upgrade.

Choose Mattermost if...

Your profile matches its sweet spot: teams that need self-hosted, privacy-first messaging
You need self-hosting, data sovereignty, or the ability to audit source code
You specifically need Channels and Compliance
You care about open source with active community
Your team size fits the mid-size teams profile Mattermost is designed for

Choose Lark if...

Your profile matches its sweet spot: teams wanting an all-in-one collaboration suite
You specifically need Calendar and Docs
You care about includes video as a core feature, purpose-built for team communication workflows
Your team size fits the any size profile Lark is designed for
The free tier works for you: free for up to 50 users