What is Nunchuk?

Nunchuk is a Bitcoin wallet built around multi-signature security. Unlike traditional single-key wallets where one seed phrase controls everything, Nunchuk allows you to require multiple independent keys to authorize transactions — for example, 2 of 3 keys must sign before funds can move.

This model eliminates single points of failure. If one hardware wallet is stolen or lost, the attacker cannot move funds without the remaining keys. If you lose one key, you can recover using the others.

Multi-Sig Architecture

Nunchuk supports m-of-n multi-signature schemes from 1-of-1 (equivalent to single-sig) up to 5-of-5. Common configurations include:

2-of-3: Two of three keys required. One key stored at home, one at a secure offsite location, one with a trusted person or institution. Losing one key still allows recovery via the other two.

3-of-5: Enterprise or high-value setups. Requires three of five keys — tolerates losing up to two keys while remaining recoverable.

Nunchuk coordinates signing between multiple hardware wallets using PSBT (Partially Signed Bitcoin Transactions), a standard that allows a transaction to be passed between signers offline.

Collaborative Wallets

A standout feature is collaborative wallets — multiple people can co-own a Bitcoin wallet, each controlling one or more keys. This is ideal for:

• Family inheritance planning: spouse holds one key, attorney holds escrow key • Business treasuries: CFO + CEO + board member each hold a key • Inheritance: funds accessible to heirs if original owner is incapacitated

Nunchuk handles the coordination layer, allowing co-signers to review and approve transactions via the app without revealing keys to each other.

Hardware Wallet Integration

Nunchuk works with COLDCARD (via NFC TAPSIGNER or microSD), Ledger, Trezor, BitBox02 and Jade. Each co-signer in a multi-sig setup can use a different hardware wallet model — you're not locked into one brand. COLDCARD users benefit from the deepest integration, with airgapped signing via PSBT files on microSD.