Chatto vs Mattermost

Comparing two open source alternatives to Slack and Discord . Use the comparison below to decide which one fits your needs.

Chatto

AGPL-3.0

A self-hosted chat application for teams and communities with video calls, voice calls, and screen sharing.

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Mattermost

Mattermost is an open source platform for secure collaboration across the entire software development lifecycle..

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Side-by-side comparison

	Chatto	Mattermost
License	AGPL-3.0	—
Self-hostable	Yes	No
GitHub Stars	2,638	38,878
Forks	117	8,927
Open Issues	208	967
Last Commit	Aug 22, 2026	Aug 22, 2026
First Released	Apr 8, 2026	Jun 15, 2015
Categories	Team Chat & Messaging Tools	Team Chat & Messaging Tools
Tags	#chat #collaboration #self hosted #privacy	—

GitHub stars over time

Chatto

Mattermost38,878

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