Chatto is a self-hosted messaging software released under an open-source license, allowing users to run it on their own hardware. It supports builds for Linux, macOS, and Windows and requires only a single executable for installation. Chatto encrypts message texts and selected durable account fields using per-user keys, ensuring that only the account owner can access their plaintext data. When a user deletes their account, the associated keys are destroyed, rendering the data unreadable. Each Chatto server is dedicated to a single community, isolating users and messages from others. The software includes built-in voice and video calls with end-to-end encryption. A paid hosting option, Chatto Cloud, is set to enter public beta soon, operating on European infrastructure while maintaining compatibility with self-hosted versions. Chatto is available for free on GitHub.