BitcoinOS is a smart contract operating system for Bitcoin that enables scalability and programmability without changing Bitcoin's core protocol. It uses zero-knowledge proofs via BitSNARK to verify off-chain computations directly on the Bitcoin blockchain.

The system facilitates the building of DeFi, rollups, and programmable assets secured by Bitcoin. Its Grail protocol allows for the trustless movement of BTC across different rollups and chains, serving as a decentralized infrastructure layer that extends Bitcoin's capabilities.