Hardware

Pocket Signer

A hardware signer that fits on a keychain. Plug it into any computer or phone over USB-C and it appears as a tiny network device — every Nostr event and every Bitcoin transaction is rendered on its screen and signed only when you physically tap approve. Keys never leave the device over the network.

Preorder — ships November Firmware source Get the browser extension

Media

Photos and demo video coming soon.

Features

Real signatures, on-deviceBIP-340 Schnorr signatures computed on the device with hardware-entropy nonces, self-verified before returning.

Tap to approveEvery event and transaction is shown on screen. Nothing signs without a physical tap.

Bitcoin PSBT reviewTaproot PSBT parsing and signing on-device — outputs, amounts, and change shown before you approve.

USB-C network linkNo drivers, no pairing. The device serves its own pages at http://10.77.7.1 and rejects requests from foreign web origins.

Multi-accountUp to 8 keypairs. Import via SD card, switch on-screen.

Air-gap optionSign PSBTs from an SD card with no network link at all.

How to use

Plug the device into your computer over USB-C.
Install the Signer Link extension, or open http://10.77.7.1 directly.
Log into any Nostr client via extension — signing requests appear on the device.
For Bitcoin: build a PSBT in nostrtx, send it to the device, review the outputs on screen, tap to sign.

FAQ

Can a website steal my keys?

No. Keys never cross the network — only signatures do. The API also rejects requests from arbitrary web origins, so pages you visit can't even read your public key without approval.

What happens if I lose the device?

Restore from your backup (SD-card export). A device PIN and encrypted key storage are on the roadmap — until then, treat the device like cash.

Does it work with real funds?

It produces real, valid signatures. As with any young signer, start with testnet or small amounts and verify everything.