Seedsigner

The SeedSigner is an open-source Bitcoin signing device built on a Raspberry Pi Zero. Unlike a classic hardware wallet, it never stores private keys permanently and communicates exclusively via QR codes — no USB data connection, no Wi-Fi, no Bluetooth. Wallet management (balances, addresses, history) happens in software like Sparrow on your computer; the SeedSigner only signs transactions. It is deliberately Bitcoin-only: less code, smaller attack surface.

Your seed lives only in RAM and is completely gone the moment power is cut — that's what "stateless" means. You can even remove the SD card after booting to guarantee nothing is ever written. A lost or stolen SeedSigner therefore contains no keys and needs neither a PIN nor a secure element. The entire security model shifts to your seed backup — which needs to be stored accordingly.

Yes — but not word by word. The SeedSigner can display your seed as a SeedQR: a compact QR code you transcribe onto a card once (the device guides you square by square) and then scan in seconds with the camera at every start. Our QR code cards come in formats for 12- and 24-word seeds as well as the smaller CompactSeedQR format. Important: the card is a full seed backup — protect it exactly like the words themselves.

On the Pi Zero v1.3 the Wi-Fi and Bluetooth modules are physically absent from the board — the device simply cannot transmit. That gives you the strongest possible guarantee that the SeedSigner is truly air-gapped and keys can never leave it. The SeedSigner software also runs on the Zero W and Zero 2 W (official releases ship without radio drivers), but only with the v1.3 you don't have to trust anyone that the radio is really off. That's why our kits and parts are based on the v1.3.

Both lead to the same device. The DIY kit is pure plug-together work: connect the camera via ribbon cable, seat the display on the GPIO header, fit it into the case — done in about 15 minutes. Soldering is only needed if you choose a Pi Zero without a pin header; with a pre-mounted header or the solderless hammer-in header it's not required at all. Building it yourself adds a supply-chain bonus: you know every single component — generic mass-market parts with no Bitcoin connection anyone could target.

Any Bitcoin wallet that supports QR codes — officially listed are Sparrow, Specter Desktop, Nunchuk, BlueWallet and Keeper, among others. The flow: your wallet shows the unsigned transaction as a QR code, the SeedSigner scans it, displays the details for review and returns the signed transaction as another QR code. Keys never move, only transaction data. Multisig is a core use case too: XPUB export, descriptor verification and signing in 2-of-3 setups are all standard features.

Four components: a Raspberry Pi Zero (v1.3 recommended), the Waveshare 1.3″ LCD with exactly 240×240 pixels (other resolutions are incompatible), a Pi Zero camera with the OV5647 sensor such as the ZeroCam, and a MicroSD card for the firmware. Most common pitfall: the Pi Zero uses the narrow CSI camera connector — standard Pi cameras need an adapter ribbon cable, while our ZeroCam ships with the right cable. Add a case (Open Pill or Open Pill Mini) and, if needed, the matching pin header — all available individually from us.