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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).

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