Chatto
A Slack- or Discord-style chat app for your team, except you run it on your own server instead of trusting a big company with every message your team sends.
🔗 Visit Chatto
Description
Teams that want Slack-like chat but can't or don't want to send every message and file through a third party's servers usually end up choosing between clunky self-hosted options or just accepting the trade-off. Chatto is a newer entry aimed squarely at that gap: a full team chat app — channels, voice and video calls, screen sharing — that you run yourself, on your own infrastructure, in the EU or wherever you choose.
Chatto is a self-hosted, single-binary application (no separate database required for a basic setup) built as a TypeScript/pnpm monorepo, open-sourced on July 8, 2026 under a mixed license (AGPL-3.0 for the core, Apache-2.0 for the UI, integrations, and docs). It has already gathered around 2,300 GitHub stars and over 1,180 commits, suggesting active development. Cloud hosting is announced as coming soon for teams that don't want to self-host at all, though it isn't available yet. External contributions are currently closed while the core team stabilizes the codebase.
💬 Our review
The short version: if data sovereignty or GDPR compliance is a real requirement for your team's chat — not just a nice-to-have — Chatto's self-hosted, single-binary design is one of the more practically deployable open-source Slack alternatives to show up recently, though it's young enough to warrant caution before betting mission-critical comms on it.
Against established self-hosted options like Mattermost or Rocket.Chat, Chatto's pitch is simplicity of deployment (single binary, no mandatory external database) rather than feature breadth — those older projects have years more integrations and enterprise tooling. The AGPL-3.0 core license is worth flagging: it's genuinely free to self-host, but if you modify the core and offer it as a network service to others, AGPL's copyleft terms apply, which teams evaluating it commercially should check with legal. With 2,300+ stars and steady commits it looks healthy for a young project, but the promised cloud-hosted option isn't live yet, and closed external contributions mean you're currently dependent on one team's roadmap. Good fit for privacy-conscious teams willing to self-host; not yet a drop-in replacement if you specifically need a managed cloud service today.
💰 Pricing
📊 Global score
🤖 AI-enriched data
Auto-hébergement gratuit (AGPL-3.0 / Apache-2.0 mixte) ; offre cloud hébergée annoncée mais pas encore disponible
Pros
Binaire unique, pas de base de données externe obligatoire pour une install basique
Appels vidéo/vocaux et partage d'écran inclus
Auto-hébergement gratuit, conformité RGPD facilitée
Développement actif (2300+ stars, 1180+ commits)
Cons
Projet jeune, moins d'intégrations que Mattermost/Rocket.Chat
Licence AGPL-3.0 sur le cœur : implications de conformité si modifié et redistribué en service réseau
Offre cloud hébergée annoncée mais pas encore disponible
Contributions externes actuellement fermées