Chatto, a self-hostable Slack/Discord rival, goes open source at v0.4

Chatto, a group chat app built solo over the past year as an alternative to Slack, Teams, and Discord, has been released as open source with support for self-hosting. A single executable runs the server and serves its own frontend, installable via Homebrew, with binaries for Linux (x86_64 and ARM64), macOS, and Windows. The developer pitches it as lightweight and fast, and privacy is a core design goal: all personal and chat data is encrypted at rest with per-user keys that are destroyed when an account is deleted, and there is no third-party tracking or analytics.

The architecture is deliberately non-federated — each server hosts one community, and users who want to join several communities connect to each server directly from the client. Voice and video calls with screen-sharing are built in and end-to-end encrypted, scaling to whatever the host’s infrastructure can handle. A companion managed service, Chatto Cloud, is heading into public beta, offering paid hosting on European-owned infrastructure with autoscaling, nightly backups, and zero-downtime upgrades, but no ads or premium tiers. The developer stresses there is no lock-in, since cloud-hosted and self-hosted servers are fully compatible.

At version 0.4, Chatto is described as production-ready but still pre-1.0, meaning breaking changes remain possible for the next 6–12 months. The 0.5 release will focus on moderation and content reporting plus polishing the multi-server client experience. Its release lands amid an increasingly commercialized team-chat market, where a genuinely free, privacy-first, self-hostable option stands out.