Today, we are excited to release the BOB Hybrid L2 vision paper. After years of working on Bitcoin scaling and DeFi, we’ve seen what’s needed to finally position Bitcoin as the backbone of decentralized finance. Pragmatism, open-mindedness and the willingness to innovate. 

That’s why we’re building BOB, the Hybrid L2 —a new paradigm combining Bitcoin’s security with Ethereum’s DeFi innovation, positioning Bitcoin as the backbone of the DeFi ecosystem. 

Unlocking Bitcoin's DeFi Potential

‍Bitcoin remains the most decentralized and trusted network, with over 300 million users and a trillion-dollar market cap. However, its role in DeFi has been limited, with most activity happening on Ethereum and other smart contract-enabled chains, leaving Bitcoin’s vast  liquidity underutilized. The small portion of BTC that is being actively used is fragmented across centralized exchanges and dozens of chains in multisig bridges.

With BOB’s Hybrid L2 design we strive to completely change the way BTC is used in finance. 

  • Today: deposit BTC into centralized exchanges or wrap to a dozen of other chains via multisig bridges. 
  • The Hybrid future: Everyone deposits assets into a BTC-secured platform that has access to native BTC liquidity… because everyone is OK to trust Bitcoin.  

Bitcoin security and trust-minimized bridging. 

Security is key to unlock Bitcoin liquidity in DeFi. The BOB Hybrid L2 in its final form will inherit Bitcoin security and support trust-minimized BTC deposits and withdrawals. While native ZK verification on Bitcoin requires a fork, BitVM allows us to create optimistic rollups and bridges with the tools we have today. Unlike multisig bridges and federated sidechains (t-of-n = honest majority), BitVM remains secure even with just a single honest node (1-of-n). For more details, see the BitVM2 paper co-authored by researchers from ZeroSync, BOB, TU Vienna and others.

Trust-minimized Ethereum bridge via Bitcoin finality.

Network effects, liquidity, and accessibility are key to a successful DeFi ecosystem. This Ethereum’s super power.To harness the best of both worlds, BOB will run a trust-minimized Ethereum bridge, providing ETH users with a seamless DeFi experience.

This "Hybrid" bridge functions like ETH L2 optimistic bridges but is uniquely powered by Bitcoin finality. An ETH L2 bridge waits for L2 finality on Ethereum. The Hybrid bridge instead checks for Bitcoin finality. In simple terms: ETH and ERC-20s deposited to BOB are secured by Bitcoin. 

To learn more about BOB’s architecture, read the Hybrid L2 whitepaper.

The Hybrid Future: Bitcoin as the DeFi Backbone

This is just the beginning. Just like there are hundreds of banks, there will exist hundreds of chains. Today, most users rely on centralized services like exchanges to swap between networks. 

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In the Hybrid future, Bitcoin-secured, interoperable platforms will replace the traditional centralized exchanges. BOB will operate Bitcoin-powered, trust-minimized bridges to any chain that can verify the Bitcoin mainchain. Ethereum, Solana, Tron, Sui, Aptos, Arbitrum, Optimism, Polkadot,... the list goes on. 

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The superpower of the Hybrid L2 is using Bitcoin as a trust-anchor to create an interoperable, Bitcoin-backed DeFi ecosystem, concentrating liquidity around Bitcoin instead of fragmenting it across chains.

Roadmap

Phase 1 (Live): Bootstrapping as ETH L2. BOB launched as an Ethereum L2, built with the OP Stack, in May and grew to 100+ projects, 170k unique users and USD 100m+ in on-chain assets. Primary focus: improve Bitcoin UX in DeFi, for example via BOB 1-click BTC staking.  

Phase 2 (WIP): ETH L2 with Bitcoin Finality. Currently under development, BOB will add a Bitcoin finality protocol to the ETH L2 setup. This means: better security, trust-minimized BTC bridge, and faster withdrawals on the native ETH bridge. 

Phase 3: Bitcoin rollup.The final step is inheriting Bitcoin security. ZK rollups require a fork to work on Bitcoin. So, the optimistic rollup via BitVM is the way to go - but requires using Bitcoin for data availability which is expensive. Meaning: transitioning to a full BTC rollup is suggested once BOB reaches sufficient scale to maintain competitive transaction fees. 

Build on BOB

We’re excited to work with builders to shape the future of Bitcoin DeFi. The BOB mainnet is live and developers are invited to use the BOB SDK to build on the intersection of BTC and EVM. The BOB Foundation will be launching grants to support developers building innovative Bitcoin use cases. 

To get involved:

  • Learn more and dive into developer docs on docs.gobob.xyz
  • Bridge assets into BOB and use across dozens of DeFi apps
  • 1-click stake BTC via BOB Stake

To stay up-to-date on BOB, follow @build_on_bob on Twitter or join the Discord. 

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