SeedSigner is the best open-source air-gapped Bitcoin signer you can build yourself.
It runs on a Raspberry Pi Zero and never touches the internet. You control the entire stack.
Official Site → seedsigner.com
- Raspberry Pi Zero 2 W (~$15)
- Waveshare 1.3" 240x240 LCD (or Waveshare 1.44" 128x128)
- 4x or 6x push buttons (6mm tactile)
- MicroSD card (16GB+ Class 10)
- 5V 1A+ USB power supply (or battery pack for true air-gap)
- Optional: 3D printed case or cardboard
1. Flash the latest SeedSigner image to your microSD card (use Raspberry Pi Imager or balenaEtcher).
2. Insert SD card into Pi Zero.
3. Wire the LCD and buttons according to the official pinout (docs have clear diagrams).
4. Power on. The device boots directly into the signer menu.
5. Generate or load your seed (never enter it on a computer).
6. Use it to sign PSBTs from your watch-only wallet (Electrum, Sparrow, etc.).
- Never reuse seeds from this device on other hardware.
- Buy parts from reputable sellers (avoid used hardware).
- Verify the image checksum when downloading.
- This is the only way to truly know your signer has not been compromised.
• Independently audit all source code and verify every checksum from official repositories only.
• DO NOT trust pre-built devices, binaries, or firmware from third parties or "convenience" sellers.
• Research the full project history, contributors, audits, and community consensus before trusting with funds.
• You bear full responsibility for your own opsec and security. DOSWAPZ provides information only.
If you want something even more minimal, you can build a basic air-gapped signer using:
- Raspberry Pi Zero + Python + bitcoinlib
- Simple OLED display + buttons
Many people in the community have open scripts for this. Search "DIY air-gapped bitcoin signer github".