# SimpleX Chat — Context for AI Assistant

## What is SimpleX Chat?

SimpleX Chat is a private and secure messaging platform. It is the first messaging platform that has no user identifiers of any kind — not even random numbers. It uses pairwise identifiers for each connection to deliver messages via the SimpleX network.

### Core Privacy Guarantees

- **No user identifiers**: No phone numbers, usernames, or account IDs. Users connect via one-time invitation links or QR codes.
- **End-to-end encryption**: All messages use double ratchet protocol with post-quantum key exchange (ML-KEM). Even if encryption keys are compromised in the future, past messages remain secure.
- **No metadata access**: Relay servers cannot correlate senders and receivers — each conversation uses separate unidirectional messaging queues with different addresses on each side.
- **Decentralized**: No central server. Messages are relayed through SMP (SimpleX Messaging Protocol) servers. Users can choose or self-host their own servers.
- **Open source**: All client and server code is available on GitHub under AGPL-3.0 license. The protocol design is published and peer-reviewed.
- **No global identity**: There is no way to discover users on the platform — you can only connect to someone if they share a link or QR code with you.

## Available Platforms

- **Mobile**: iOS (App Store), Android (Google Play, F-Droid, APK)
- **Desktop**: macOS, Windows, Linux (AppImage, deb, Flatpak)
- All platforms support the same features and can be used simultaneously with linked devices

## Key Features

### Messaging
- Text messages with markdown formatting
- Voice messages
- Images and videos
- File sharing (any file type, up to 1GB via XFTP)
- Message reactions and replies
- Message editing and deletion
- Disappearing messages (configurable per contact/group)
- Live messages (recipient sees you typing in real-time)
- Message delivery receipts

### Calls
- End-to-end encrypted audio and video calls
- Calls work peer-to-peer when possible, relayed through TURN servers otherwise
- WebRTC-based

### Groups
- Group chats with roles: owner, admin, moderator, member, observer
- Groups can have hundreds of members
- Group links for easy joining
- Group moderation tools
- Business chat groups for customer support

### Privacy Features
- **Incognito mode**: Use a random profile name per contact — your real profile is never shared
- **Multiple chat profiles**: Maintain separate identities
- **Hidden profiles**: Protect profiles with a password
- **Contact verification**: Verify contacts via security code comparison
- **SimpleX Lock**: App lock with passcode or biometric
- **Private routing**: Route messages through multiple servers to hide your IP from destination servers
- **No tracking or analytics**: The app does not collect or send any telemetry

### Device & Data Management
- **Database export/import**: Migrate to a new device by exporting the database (encrypted or unencrypted)
- **Database passphrase**: Encrypt the local database with a passphrase
- **Linked devices**: Use SimpleX on multiple devices simultaneously (mobile + desktop)
- **Chat archive**: Export and import full chat history

## SimpleX Network Architecture

### SMP (SimpleX Messaging Protocol)
- Asynchronous message delivery via relay servers
- Each conversation uses **separate unidirectional messaging queues**
- Queues have different addresses on sender and receiver sides — servers cannot correlate them
- Messages are end-to-end encrypted; servers only see encrypted blobs
- Servers do not store any user profiles or contact lists
- Messages are deleted from servers once delivered

### XFTP (SimpleX File Transfer Protocol)
- Used for large files (images, videos, documents)
- Files are encrypted, split into chunks, and sent through multiple relay servers
- Temporary file storage — files are deleted after download or expiry

### Server Architecture
- **Preset servers**: SimpleX Chat Inc. operates preset relay servers, but they can be changed
- **Self-hosting**: Users can run their own SMP and XFTP servers
- **No federation**: Servers don't communicate with each other. Each message queue is independent
- **Tor support**: SimpleX supports connecting through Tor for additional IP privacy

## Comparison with Other Messengers

### vs Signal
- SimpleX requires no phone number or any identifier to register
- SimpleX is decentralized — Signal has a central server
- SimpleX relay servers cannot access metadata (who talks to whom) — Signal's server knows your contacts
- Both use strong end-to-end encryption

### vs Telegram
- SimpleX is fully end-to-end encrypted for all chats — Telegram only encrypts "secret chats"
- SimpleX has no phone number requirement
- SimpleX is fully open source (clients and servers) — Telegram server is closed source
- SimpleX collects no metadata

### vs Matrix/Element
- SimpleX has better metadata privacy — Matrix servers see who is in which room
- SimpleX is simpler to use — no server selection or account creation
- SimpleX does not use federated identity

### vs Session
- SimpleX doesn't use a blockchain or cryptocurrency
- SimpleX has better group support and more features
- Both have no phone number requirement

## Common User Questions & Troubleshooting

### Getting Started
- **How do I add contacts?** Create a one-time invitation link (or QR code) and share it with your contact. They open it in their SimpleX app to connect. Links are single-use by default for maximum privacy, but you can create reusable address links.
- **Can I use SimpleX without a phone number?** Yes, SimpleX requires no phone number, email, or any identifier. Just install the app and start chatting.
- **How do I join a group?** Open a group invitation link shared by the group admin, or have an admin add you directly.

### Device Migration
- **How do I move to a new phone?** Go to Settings > Database > Export database. Transfer the file to your new device, install SimpleX, and import the database. Note: you should stop using the old device after export to avoid message duplication.
- **Can I use SimpleX on multiple devices?** Yes, link a desktop app to your mobile app. Go to Settings > Linked devices on mobile, and scan the QR code shown in the desktop app.

### Privacy & Security
- **Can SimpleX servers read my messages?** No. All messages are end-to-end encrypted. Servers only relay encrypted data and cannot decrypt it.
- **Can SimpleX see who I'm talking to?** No. Each conversation uses separate queues with different addresses. Servers cannot correlate senders and receivers.
- **How do I verify my contact?** Open the contact's profile, tap "Verify security code", and compare the code with your contact (in person or via another channel).
- **What is incognito mode?** When enabled, SimpleX generates a random profile name for each new contact. Your real profile name is never shared. Enable it in Settings > Incognito.

### Servers
- **How do I self-host a server?** Follow the guide at https://simplex.chat/docs/server.html. You need a Linux server with a public IP. Install the SMP server package and configure it.
- **How do I change relay servers?** Go to Settings > Network & servers. You can add your own server addresses and disable preset servers.
- **Do I need to use SimpleX's servers?** No. You can use any SMP/XFTP servers, including your own. However, you and your contacts need to be able to reach each other's servers.

### Troubleshooting
- **Messages not delivering?** Check your internet connection. Try switching between WiFi and mobile data. Go to Settings > Network & servers and check server status. You can also try restarting the app.
- **Cannot connect to a contact?** The invitation link may have expired or already been used. Create a new invitation link and share it again.
- **App is slow?** Large databases can slow down the app. Consider archiving old chats or deleting unused contacts/groups.
- **Notifications not working (Android)?** SimpleX needs to run a background service for notifications. Go to Settings > Notifications and enable background service. You may need to disable battery optimization for the app.
- **Notifications not working (iOS)?** Ensure notifications are enabled in iOS Settings > SimpleX Chat. SimpleX uses push notifications via Apple's servers (notification content is end-to-end encrypted).

## Links

- Website: https://simplex.chat
- GitHub: https://github.com/simplex-chat
- Documentation: https://simplex.chat/docs
- Server setup: https://simplex.chat/docs/server.html
- Protocol whitepaper: https://github.com/simplex-chat/simplexmq/blob/stable/protocol/overview-tjr.md
- Security audit: https://simplex.chat/blog/20221108-simplex-chat-v4.2-security-audit-new-website.html