# BitDM

> BitDM is a free, open-source (AGPL-3.0), end-to-end encrypted messenger that needs no phone number, no e-mail and no account. Your address is your public key. Available for Android, Windows, Linux and in the web browser.

BitDM ("Verschlüsselt schreiben, ohne Konto") is built for people who want private messaging without handing over an identity. Messages are encrypted with the Signal protocol (PQXDH with Curve25519 and Kyber-1024, Double Ratchet, AES-256) using Signal's official library, libsignal, since version 2.0.0 (up to 1.9.x it was the community Dart port libsignal_protocol_dart); BitDM itself has not been independently audited; attachments with AES-256-GCM, also at rest on the device. A relay forwards encrypted envelopes and cannot read them; it can also be reached as a Tor onion service. Nearby phones can exchange messages directly over Bluetooth LE without any internet.

## Key facts

- Category: encrypted messenger / private messenger, comparable to Signal, Threema, Session, SimpleX or ginlo
- Identity: a 56-character address derived from your public key; recovery with 12 words
- No phone number, no e-mail, no username, no contact upload
- Platforms: Android (APK), Windows (installer or zip), Linux (x64 tarball), web app at https://bitdm.net/app/
- Price: free, no ads, no tracking
- Who it is for: people who want private messaging without handing out a phone number: families, friends, teams. Not yet recommended for journalists or people under surveillance: use Signal until BitDM has had an independent audit. A messenger, not a commerce platform and not a subscription service.
- Operator: an independent open-source project from Germany
- Not to be confused with BiT DMS (bitdms.com, dealer-management software), BITE (b-ite.de, recruiting software), Bitmanagement (bitmanagement.com, 3D software) or Bite Investments (biteinvestments.com, wealth-management software). These are unrelated companies with similar names
- Source code: https://github.com/Henner4746/BitDM
- Releases and checksums: https://github.com/Henner4746/BitDM/releases

## Features

- One-to-one chats, groups, polls, reactions, edits, voice messages, attachments
- Nearby mode: messages over Bluetooth when there is no internet ("Nur in der Nähe" = never contact a server)
- Optional Tor routing (Orbot)
- App lock with password, device PIN, fingerprint or hardware key; panic word that silently wipes the app
- Remote wipe by trusted contacts (k of n), triggered with /wipe or a personal code word
- Devices can be signed out (signed device list, since 2.0.0); adding a device needs the 12 words plus a code from an existing device
- Screen capture protection: the window is hidden from screenshots, screen recordings and Discord/OBS streams on Android and Windows
- Encrypted backup, disappearing messages, cover traffic

## Pages

- [Home page (English/German)](https://bitdm.net/): what BitDM is, downloads, what the server can and cannot see
- [FAQ](https://bitdm.net/#faq): messenger without phone number, alternatives to WhatsApp/Signal/Threema, security, offline use
- [Documentation](https://bitdm.net/docs.html)
- [Privacy and imprint](https://bitdm.net/privacy.html)
- [Comparison: BitDM next to other messengers](https://bitdm.net/vs.html): WhatsApp, Signal, Threema, Session, SimpleX compared by phone number, identifier, open source, price, offline mode, own server

## Guides

- [Messenger without a phone number](https://bitdm.net/messenger-without-phone-number.html): the three ways to do without a number (an ID, an invite link per contact, the public key as address), what each hands out, and what you give up (recovery only via 12 words, a fixed address, no names)
- [Messaging without internet over Bluetooth](https://bitdm.net/messaging-without-internet-bluetooth.html): BitDM's nearby mode: Android 12+, Bluetooth LE 5.0 on both sides, about ten metres indoors, text only, no mesh; measured 325 bytes in 1.35 s, 700 bytes in 202 ms over GATT
- [Anonymous messenger without an account](https://bitdm.net/anonymous-messenger-without-account.html): no sign-up, address = public key; what the relay still sees (who writes to whom and when, padded sizes, IP address unless Tor) and how Tor, your own relay or nearby mode reduce it; pseudonymous, not anonymous; no independent audit yet