What is the difference between Mattermost and Flock?

Mattermost is best for Teams that need self-hosted, privacy-first messaging, while Flock is best for Teams wanting messaging with built-in productivity tools. Mattermost starts at Free (self-hosted) and Flock starts at Free.

Is Mattermost or Flock cheaper?

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

Is there a free alternative to Flock?

Both Mattermost and Flock offer free tiers.

Mattermost vs Flock

Mattermost is open-source, self-hosted team messaging platform for organizations that need data sovereignty, while Flock is team messaging with built-in to-dos, polls, notes, and file sharing. 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 Flock targets teams wanting messaging with built-in productivity tools.

At a glance

	Mattermost	Flock
Best for	Teams that need self-hosted, privacy-first messaging	Teams wanting messaging with built-in productivity tools
Starting price	Free (self-hosted)	Free
Free tier	✓	✓
Open source	✓	—
Free tier available	✓	✓
Open source	✓	—
Channels	✓	—
Compliance	✓	—
Integrations	✓	—
Notes	—	✓
Playbooks	✓	—
Polls	—	✓
Self-Hosted	✓	—
To-Dos	—	✓
Video Calls	—	✓

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

Flock

Strengths

Lightweight to-do lists keep daily tasks front and center without project-management overhead
Includes Polls as a core feature, purpose-built for team communication workflows
Free for up to 20 users — generous enough for most small teams to get real work done
Established product with 12+ years on the market and a mature ecosystem

Weaknesses

Free plan exists but key features are locked behind the paid upgrade
Fewer built-in features means you may need additional tools to cover gaps
Notification overload is a real problem as the number of channels grows
Limited team/admin features if your organization eventually scales up

Try Flock → Full review

The bottom line

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

Feature gaps: Mattermost offers Channels, Compliance and Integrations that Flock lacks. Flock brings Notes, Polls and To-Dos that Mattermost does not have.

Team fit: Mattermost is geared toward mid-size teams teams, while Flock is aimed at small teams 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. Flock 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. Flock's biggest strengths are: lightweight to-do lists keep daily tasks front and center without project-management overhead. includes polls 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 Flock, 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 Flock if...

Your profile matches its sweet spot: teams wanting messaging with built-in productivity tools
You specifically need Notes and Polls
You care about includes polls as a core feature, purpose-built for team communication workflows
Your team size fits the small teams profile Flock is designed for
The free tier works for you: free for up to 20 users