Layer-2 blockchain network Build on Bitcoin (BOB) has raised $21 million in strategic funding rounds since December 2024, with $9.5 million secured in its latest round, according to a press release sent to Cryptox.
Many existing investors have increased their financial commitments in the latest $9.5 million strategic round, including exiting investor Castle Island, along with new strategic investors Anchorage, Amber Group and sats Ventures.
Nic Carter, founding partner of Castle Island, told Cryptox why they have decided to double down on their investment:
“We also continue to believe that Bitcoin will be the bedrock of DeFi, and we think BOB will be a marquee L2.”
Dominik Harz, chief technology officer at BOB, told Cryptox the company’s next major milestone is launching the BitVM bridge into production. The bridge would enable native Bitcoin (BTC) to be used in DeFi on BOB and facilitate BTC transfers to other chains.
BOB plans to launch BTC-staked finality by the end of 2025, with future upgrades enabling BTC-secured bridges to Solana, Ethereum, Sui and other smart contract chains.
“Users, institutions, apps and wallets everywhere will be able to access native BTC DeFi via BOB,” Harz said.
BOB’s testnet recently went live with support from partners including Lombard, Amber Digital and RockawayX. A mainnet launch is planned for the fourth quarter of 2025.
Bridging Bitcoin and Ethereum
BOB uses the hybrid chain model, which combines the security and stability of Bitcoin with the versatility of Ethereum’s DeFi ecosystem.
BOB is a hybrid because it is simultaneously a member of the Superchain, leveraging the OP Stack as an Ethereum rollup, and also a Bitcoin-secured network, integrating with Babylon for Bitcoin finality via billions of dollars of staked BTC.
As of Aug. 7, 2025, BOB’s total value locked is $212 million, DeFi TVL is $132.2 million, with 553,000 users.
Related: Build on Bitcoin adds ZK-proofs in upgrade toward decentralization
Native Bitcoin DeFi is on the way
Previously, Bitcoin DeFi largely relied on centralized institutions or wrapped Bitcoin tokens such as wBTC (wBTC), tBTC (TBTC) and Huobi BTC (HBTC). These so-called “Bitcoin” tokens were representations of real BTC, where users deposited their genuine BTC with a centralised or multisignature custodian in exchange for a tokenised version that could be used onchain.
While all BTC bridges have historically relied on multisignature custody, BOB’s BitVM2 allows users to interact with DeFi applications using their native BTC directly—no custody, no wrapping required.
BitVM2 is the latest BitVM design, co-authored by BOB co-founder Alexei Zamyatin. It enables practical fraud proofs on Bitcoin, which allows users to enforce trust-minimized bridging between the Bitcoin L1 and BOB.
By leveraging this technology, BOB aims to bring Bitcoin closer to Ethereum-style decentralized finance, allowing Bitcoin users to engage in DeFi without losing control of their assets. The network aims to preserve Bitcoin’s security while enabling interaction with Ethereum-based DeFi protocols.
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