SeedSigner

SeedSigner is a free, open-source DIY Bitcoin signing device built from a Raspberry Pi-compatible board, camera, display and microSD card. It is a stateless signer for single-signature and multisignature Bitcoin wallets, not a retained-key wallet or a broad multi-asset portfolio device.

Stateless seeds and a physical QR air gap

SeedSigner loads a seed into working memory for setup or signing and clears it when power is removed. It does not retain the seed or wallet configuration after shutdown. The recommended Raspberry Pi Zero v1.3 has no Wi-Fi or Bluetooth hardware, while the device receives data through its camera and returns data through QR codes on its display.

This differs from a Secure Element-based device that retains keys internally. SeedSigner's design relies on temporary in-memory seeds, QR-only exchange, a minimal signing operating system and components a user can assemble and inspect. Removing the microSD card after the operating system loads can also reduce the chance of seed data being written to it during ordinary signing.

A coordinator builds the PSBT; SeedSigner adds the signature

SeedSigner can create or import a 12- or 24-word BIP39 seed, with an optional passphrase, and export an extended public key as QR data. A coordinator such as Sparrow, Specter Desktop or Nunchuk uses that public information and the wallet policy to create addresses and watch balances without requiring the signer to stay powered on.

To spend, the coordinator displays a PSBT as animated QR frames. SeedSigner scans it, shows transaction information and relevant outputs for review, then returns a QR sequence containing its signature after approval. The coordinator combines any required signatures and broadcasts the final Bitcoin transaction; SeedSigner neither connects to the Bitcoin network nor broadcasts it.

Multisignature and descriptor recovery are first-class concerns

Several SeedSigner-derived extended public keys can be joined with other signers in a policy such as two of three, requiring a quorum rather than one device signature. The device can also verify receive and change addresses and supports multiple Bitcoin script types and custom derivation paths.

Stateless operation makes a replacement device possible from standard parts and the original backup, but the owner must preserve the seed, any passphrase and enough wallet descriptor information to reconstruct the policy and verify addresses. SeedQR offers a hand-transcribed way to reload a seed, alongside manual word entry.

DIY QR signing versus purpose-built hardware

Ledger is the main contrast for a user deciding between a ready-made multi-chain signer and a Bitcoin-specific DIY setup. Ledger uses a Secure Element, connects by USB or Bluetooth depending on model and works with Ledger Wallet; SeedSigner is Bitcoin-only, stateless, QR-air-gapped and built from Raspberry Pi components.

Coldcard is the closer Bitcoin-focused commercial comparison. Both support offline signing and multisignature, but SeedSigner emphasizes camera-based QR exchange and temporary seed loading, while Coldcard uses purpose-built hardware and microSD-oriented workflows. SeedSigner rewards a technically inclined owner who is prepared to source compatible parts, assemble the device and verify its software image.