ArcaChat

Encrypted chat that uses Gmail as transport. No servers, no data storage, no middleman.

Messages are encrypted with AES-256-GCM on your device before being sent as emails via the Gmail API. Only you and your contact (who share a password) can read them.

How it works

• You type a message → it's encrypted on your PC → sent as a Gmail email
• Recipient's ArcaChat picks it up → decrypts it locally → displays it
• Gmail only ever sees encrypted ciphertext
• No chat server. No message database in the cloud. Nothing to hack or subpoena.

Quick start (Windows)

1. Download ArcaChatInstaller.zip from Releases
2. Extract and double-click ArcaChatInstaller.exe
3. Sign in with Google
4. Add a contact by their Gmail address — done

For developers

The entire app is two files:

• server.py — Python backend (Gmail API, encryption, WebSocket server)
• static/index.html — React frontend (single file, no build tools)

To run from source:

pip install aiohttp google-api-python-client google-auth-httplib2 google-auth-oauthlib cryptography
python server.py

You'll need a credentials.json from Google Cloud Console (Gmail API, OAuth 2.0 Desktop app).

Tech

• Encryption: AES-256-GCM, per-contact shared passwords
• Transport: Gmail API (OAuth2, no app passwords)
• Backend: Python, aiohttp, SQLite
• Frontend: React 18, single HTML file, no build step
• Build: PyInstaller for Windows .exe

Status

Early prototype — looking for testers. If you have a Gmail account and 5 minutes, I'd love your help. Open an issue or reach out.