A bridge releases money on one chain because something happened on another, and a verifier in the middle decides whether the claim is true. Nomad, BNB Chain's Token Hub, and Hyperbridge each made that verifier check a Merkle proof, and each accepted a forged one, about $750M between them. Where each check stopped short, and what a verifier has to be anchored to.

In April, KelpDAO's rsETH bridge was hacked for about $292M. The attacker got Ethereum to release the funds against a burn on Unichain that never happened. Nobody stole a key. The verifier asked an RPC node what happened, and the node lied. Here's how it worked, and what changes when a verifier checks a proof instead of a report.

Willow runs as its own chain, and its entire state is a single hash its validators sign into every block. A contract on Ethereum mainnet verified a proof of that consensus, stored the root, and checked a record from Willow's state against it. Ethereum contracts can now act on anything Willow indexes or stores, with no oracle in between.

A contract on Ethereum mainnet verified that a sequence of consecutive Base blocks had been indexed completely and correctly, and that the sequence was a real, finalized stretch of Base itself. Ethereum contracts can now execute on indexes of Base events without a trusted oracle or relayer.

Merkl is running a live rewards campaign on a Uniswap v4 pool. We proved the whole set of pool events behind it, every Swap and ModifyLiquidity across eight mainnet blocks with none missing, and a contract on Ethereum verified it for a few cents.

Lido's on-chain balance comes from nine oracle operators voting on what an off-chain indexer told them. This week an Ethereum mainnet contract verified the same figure without a vote - the exact registered validator set and its consensus-layer balance, at a single finalized slot, in one transaction.

We deployed a contract to Ethereum mainnet that checked a Willow completeness proof — confirmation, on-chain, that a window of blocks was indexed with nothing left out, anchored to the real canonical chain. Here's how it works and what it unlocks.

Tokenizing a fund puts its shares on-chain, but not its books. Those still come from indexers that read and interpret the chain — so reconciliation does not disappear. It becomes a new question: does the off-chain record actually match the chain?

I fell in love with Web3's promise of a trustless, verifiable future, then watched most apps give it up at the indexing layer. Here's why I built Willow to get it back.

Most of the data your apps consume is unverifiable. We're introducing Willow — verifiable data infrastructure, every step backed by a cryptographic proof.