simplex-chat: Private Messaging Without User Identifiers

Overview

SimpleX Chat is a messaging platform built around a different way to route conversations: it uses disposable, pairwise message queues rather than assigning users persistent identifiers. Its goal is to limit what messaging services and network observers can learn about who is connected to whom, alongside protecting message contents with end-to-end encryption.

The project includes Android and iOS apps, a desktop client, and a terminal client. It is aimed at people who prioritize privacy and are willing to make connections by sharing an invitation link or QR code. The project also provides protocols and tools for developers building bots or integrations.

Key Features

• No platform-assigned user identifiers, with separate message queues for conversations.
• End-to-end encryption using a double ratchet, plus an additional encryption layer for messages.
• Private message routing intended to help protect users' IP addresses from unknown relays.
• Mobile apps for Android and iOS, a desktop client, and a terminal client for Linux, macOS, and Windows.
• Messaging features including groups, files, voice messages, and audio and video calls.
• Optional Tor access to messaging servers and encrypted local chat databases.
• Developer support for chat bots and integrations, including a CLI WebSocket interface and TypeScript client.

Use Cases

• Individuals who want encrypted conversations without a persistent account identifier or publicly discoverable contact handle.
• People who want to reduce exposure of their social graph and message metadata, and can establish contacts through invitation links or QR codes.
• Privacy-conscious groups that need encrypted group chats and file sharing.
• Developers building chat bots, automations, or app integrations on the SimpleX platform.

Project Facts

• Language: Haskell
• License: AGPL-3.0
• Stars: 19.5k
• Forks: 1.4k
• Topics: chat, double-ratchet, e2ee, encryption, haskell, messaging, privacy, protocol, security
• Archived: false

Getting Started

Install the terminal client with:

curl -o- https://raw.githubusercontent.com/simplex-chat/simplex-chat/stable/install.sh | bash

Then run simplex-chat. For mobile apps and other installation options, see the repository README.

Considerations

The project describes itself as a work in progress and notes that users should assess whether its current state fits their needs. Its privacy design depends on users sharing invitation links or QR codes to make connections, and the default servers are provided on a best-effort basis without an SLA. The repository also notes that client builds are not yet reproducible. The AGPL-3.0 license applies to the software, while branding and graphic assets have separate terms.