Open-source Bitcoin multisig coordinator: shared signing queue, hardware wallets, live signet demo

The newly released open-source project, btc-safe, is a self-hosted, watch-only Bitcoin multisig coordinator designed to enhance the security and efficiency of managing multisignature transactions. This tool enables one owner to propose transactions which are then visible to all co-signers in a shared queue. Each co-signer can sign the transaction independently from their own device. The transaction is broadcasted only after a predefined minimum number of approvals (M of N) is reached, ensuring a high level of security and consensus before any funds are moved.

btc-safe operates strictly as a watch-only service; it stores extended public keys (xpubs) and wallet descriptors but does not hold any private keys nor does it perform any signing operations itself. This feature significantly enhances the security of the system by minimizing the attack surface. Additionally, btc-safe includes mechanisms for independent verification: the browser component re-derives change and receive addresses using the provided xpubs and cross-verifies every Partially Signed Bitcoin Transaction (PSBT) against the server’s data, adding an extra layer of trust and validation to the process.

The platform supports various hardware wallets and software solutions for signing transactions, including Ledger, Trezor, Sparrow, Caravan, and direct PSBT file imports. It also offers robust account management features such as Time-based One-Time Password (TOTP) two-factor authentication and configurable per-wallet roles like admin, proposer, and viewer. Furthermore, the system is reorganization-aware, which helps confirmations remain accurate even in the event of a blockchain reorganization.

Developed using modern technology stacks, btc-safe utilizes Rust with libraries such as axum and bdk_wallet for backend processes, PostgreSQL for database management, and Next.js for the frontend development. It is distributed under the MIT license, allowing for wide usage and contribution from the developer community.

For those interested in testing the functionality without risking real funds, a trial version is available on a signet test network. Users can try it here by signing up with any email address, creating a 2-of-3 wallet, and funding it through a signet faucet. The complete codebase is accessible on GitHub for anyone wishing to explore the implementation details or contribute to the project. The repository can be found at this GitHub link.