Skip to main content

What is BOB

BOB ("Build on Bitcoin") is a new BTC L2 stack with full EVM compatibility, combining Bitcoin's security and power as the most widely adopted digital asset with Ethereum's programmability, scalability and user experience. BOB is designed to be a Bitcoin co-processor, enhancing Bitcoin's functionality and using the Bitcoin L1 for settlement, custody and storage:

  • Bitcoin security. BOB allows to inherit Bitcoin PoW security, with the long-term goal to achieve optimistic rollups on the Bitcoin L1 via on-chain fraud proofs using mechanisms like BitVM.
  • Support for the Bitcoin stack. BOB supports the existing Bitcoin tech stack, incl. Ordinals, Lightning and Nostr, powered by cross-chain light clients, a universal Bitcoin smart contract SDK, and a Rust zkVM
  • EVM smart contracts. BOB smart contracts are powered by the EVM, ensuring full compatibility with best-in-class infrastructure and tooling.
  • ETH rollup support. BOB supports rolling up to Ethereum as an OP stack rollup to unlock Bitcoin use cases for web3 power users. This way, BOB benefits from native support for all ERC20 tokens (incl. USDC, USDT, ETH), access to DeFi liquidity, and as easy on/off-ramps from major exchanges and institutional platforms.

The BOB Stack

BOB Stack

Rollup Layer

Bitcoin PoW security, native Ethereum bridge. Outlook: BitVM

As the base layer, BOB can use any EVM rollup or chain. Initially, BOB launches on the OP stack including the upcoming ZK improvements by RiscZero and can be rolled up to Ethereum for 1-click onboarding of users, assets and liquidity. In addition, BOB can inherit Bitcoin security via a novel merged mining protocol (re-staking for Bitcoin). BOB's ultimate goal is to settle directly on the Bitcoin L1. While we believe in full-state validation via ZK rollups in the long run, it is very unlikely that Bitcoin will support a ZK verifier in the near future. As such, the currently best possible design is an optimistic rollup that leverages on-chain fraud-proofs via mechanisms like BitVM.

EVM Core

Smart Contracts and Best-in-Class Infrastructure & Dev Tooling

At the core, BOB leverages the Ethereum Virtual Machine (EVM) to enable the creation and execution of smart contracts, primarily developed using the Solidity smart contract programming language. The EVM version deployed on BOB will be equivalent to that of Ethereum, ensuring compatibility with existing developer tooling (Hardhat, Foundry, Remix, …), wallets (Metamask, WalletConnect supported wallets,...), best-in-class multisig (Safe), as well as key infrastructure, including block explorers like BlockScout and data analytics (TheGraph, Dune, GoldSky).

Rust zkVM

ZK tooling and support for Bitcoin's Rust libraries.

The majority of Bitcoin’s stack and applications built around it are implemented in Rust, including core SDKs, Lightning, and Ordinals. BOB can support Bitcoin’s Rust libraries, most notably via the RISC Zero zkVM that allows off-chain execution of Rust programs while using ZK proofs to verify correct execution in EVM smart contracts. In the future, we see this as an avenue for ZK rollups directly on Bitcoin where BOB itself can be proven in the zkVM and verified by Bitcoin consensus.

Bitcoin Bridges

Trustless P2P swaps, threshold cryptography and insurance for wrapping. Outlook: BitVM

BOB provides trustless access to Bitcoin block and transactional data via a BTC light client, allowing EVM contracts to process BTC transactions (e.g. P2P BTC swaps, Ordinal auctions, hashrate tokenization,...). BOB also supports a range of Bitcoin bridges, both decentralized and institutional. Through a native ETH L1/L2 bridge, BOB has access to market leader wBTC and the more secure, threshold-based version, tBTC v2. BOB will support advanced bridge models including opt-in collateralization (see iBTC). In the future, BOB aims to introduce a 2-way light-client BTC bridge powered by BitVM.


A smart contract deveopers' universal toolkit for all things building on Bitcoin

Similar to OpenZeppelin and other great Solidity libraries, BOB provides a powerful SDK for all things building on Bitcoin. This includes a wide range of Solidity contracts that can be used to interact with Bitcoin including core, Ordinals, BRC20s, and Lightning, as well as improved inscription APIs and tools for a unified BTC and EVM wallet experience (e.g. manage Ordinals in your MetaMask wallet via Snaps). Plus the ability to leverage Account Abstraction with bridged BTC.