SimpleX Chat

SimpleX Chat is a privacy-focused messaging system built to minimize metadata by avoiding global user identifiers (no phone numbers, usernames, or accounts). It uses the SimpleX messaging protocol and relay servers to deliver end-to-end encrypted messages while aiming to keep social graphs and contact discovery off centralized infrastructure.

Key Features

• No user IDs: contacts are added via invitation links/QR codes rather than usernames or phone numbers
• End-to-end encryption with authentication and forward secrecy-oriented session design (protocol-level encryption)
• Relay-based message delivery using SimpleX servers; clients can use public relays or run their own
• Private contact connections and group messaging (group participation without public identity)
• File and media attachments with encrypted transport
• Multi-device support (via app clients) and cross-platform availability (desktop/mobile)

Use Cases

• Secure 1:1 and group conversations for communities that cannot rely on phone-number identity
• Private coordination for teams or activists needing reduced metadata exposure
• Self-operated relays for organizations that want control over message transport infrastructure

Limitations and Considerations

• Contact onboarding relies on exchanging invite links/QRs, which can be less convenient than directory-based messengers
• Some features and UX may vary by client platform as the ecosystem evolves

SimpleX Chat is a strong option when the primary goal is private messaging with minimal metadata and without account-based identity. Its relay-based architecture and support for running your own servers make it suitable for both personal and organizational deployments where privacy properties matter most.