The short answerSeedSigner is a stateless Bitcoin signing device you build yourself from a Raspberry Pi Zero, a camera and a screen. It stores no key between sessions, has no vendor to breach or shut down, and demands real technical confidence and comfort with air-gapped PSBT workflows.
Best forStateless, self-built Bitcoin signing
Key isolationweight 25%
7.5avg 8.6
Firmware opennessweight 20%
10.0avg 7.8
Recovery designweight 20%
8.0avg 8.1
Asset coverageweight 15%
4.0avg 7.3
Vendor conductweight 10%
9.5avg 7.9
Usabilityweight 10%
5.5avg 8.1
this service category average across 15Score = Σ mark × weight. Works well for a specific use case, weaker outside it. Methodology.
| Criterion | Mark | What we found | Source | Checked |
|---|
| Key isolation | 7.5 | not sourced yet | not sourced yet | — |
| Firmware openness | 10.0 | not sourced yet | not sourced yet | — |
| Recovery design | 8.0 | not sourced yet | not sourced yet | — |
| Asset coverage | 4.0 | not sourced yet | not sourced yet | — |
| Vendor conduct | 9.5 | not sourced yet | not sourced yet | — |
| Usability | 5.5 | not sourced yet | not sourced yet | — |
What we liked, and what fell short
Liked- Completely open, assembled from parts anyone can source
- Stateless: no key is ever stored on the device
- No vendor to trust, breach or shut down
Fell short- Requires assembly and comfort with PSBT workflows
- No secure element and Bitcoin only
Why the marks landed where they did
Every other device in this category asks you to trust a manufacturer, a supply chain and a shipping route. SeedSigner removes all three: you buy generic parts, flash open-source firmware, and the resulting device forgets your key the moment it loses power.
How stateless signing works
You enter your seed phrase at the start of a session, sign the transaction, and power the device down. Nothing persists. That eliminates the entire category of attacks against a stored key and shifts the burden onto your physical backup, which is where it arguably belongs. Transactions move by QR code with a watch-only wallet such as Sparrow.
What it does not have
No secure element, so a device powered on with a seed loaded is vulnerable to physical attack during that window. No support for anything but Bitcoin. No vendor support at all — the project is community-maintained, documentation is good, and you are your own help desk.
Multisig and diversity
SeedSigner is particularly useful as one key in a multisig quorum, where vendor diversity is good practice and the cost of an extra device matters. Several SeedSigners built by different people from different parts is a genuinely robust arrangement.
Who should use it
Technically confident Bitcoin holders who want to remove vendor trust entirely, and multisig users building quorums. Anyone who would find assembly or PSBT workflows daunting should buy a finished device instead.
FAQ
Is SeedSigner safe without a secure element?+
Between sessions it holds no key at all, which removes stored-key attacks entirely. During a signing session with the seed loaded, physical attack is possible, so use it privately.
How much does SeedSigner cost?+
Around $50 in commodity parts — a Raspberry Pi Zero, a camera module, a small screen and a case.
Does SeedSigner support Ethereum?+
No. It is Bitcoin-only, using standard PSBT workflows with wallets such as Sparrow.
Why build your own device?+
It removes vendor trust, supply-chain tampering and the risk of a company breach exposing your customer data — which has happened to more than one hardware wallet vendor.
