Common questions.
What people ask us most. Don't see yours? Email info@willow.tech or join the Discord.
What is Willow?
Willow is the first cryptographically verifiable blockchain indexer. It serves blocks, transactions, receipts, and logs from seven chains over a standard JSON-RPC endpoint, verifies every block against the chain before serving it, and proves any log query is real and complete when you ask for a proof.
How is Willow different from other RPC providers and indexers?
Willow verifies every block before serving it, and for any log query it can give you a proof that every log is really in its block and that none were left out. You verify that proof yourself, in your browser or on your own machine, so you don't have to take our servers' word for what they returned.
What does "verifiable" mean here?
Two things. First, every block Willow serves is verified against its block hash, and so is the chain it belongs to: with the Helios light client on Ethereum, and with the sequencer's signature on the other six chains.
Second, when you ask, Willow gives you a proof of a log query that you verify yourself. It shows every log in the answer is really in its block, and that no matching log is missing. To verify it, you trust one block hash, which you confirm with a node you choose, plus SP1 and the proving programs the verifier pins. The docs list exactly what you trust.
Which chains do you support?
Seven: Ethereum, Base, Arbitrum One, OP Mainnet, Unichain, Ink, and Robinhood Chain. One key works on all of them. If you need another chain, tell us.
Does it serve balances and eth_call?
Yes, on Pay as you go, Builder, and Scale. Balances, nonces, code, storage, and eth_getProof are verified against the state root of a verified block on all seven chains, and eth_call on Ethereum runs over state verified the same way. Sending transactions and gas estimates are forwarded to a provider. The Free plan doesn't include state methods, and a custom plan includes them only if its agreement does. The docs have the details.
What doesn't it do?
It doesn't serve eth_call on the six chains other than Ethereum, filter methods like eth_newFilter, debug and trace methods, WebSockets, or subscriptions. Those return error -32601, so a router that puts Willow next to your usual provider can send them there.
How far back does the data go?
Willow keeps everything it serves, and Ethereum is held in full from genesis. On the other six chains, blocks older than Willow holds are fetched the first time a paying account asks for them, verified, and kept for everyone, so the first query over an old range is slower and the ones after it are fast.
How much does it cost?
You can start free, with 10M units a month and no card. After that, pay as you go from $10, or choose Builder or Scale. For high volume, a custom plan has per-request pricing, invoiced monthly, and higher rate limits. Proofs are a flat price per block. The pricing page has the details.
Can AI agents use it?
Yes. Once someone signs up with an email address and creates a key, an agent uses Willow RPC like any other client. It can read every price as JSON at api.willow.tech/v1/prices, and verify a proof itself instead of taking Willow's word for the data.
Is Willow open source?
The browser verifier is public in willow-verify (MIT), with the program keys it pins and a script that verifies the page Willow serves is built from it. The proving programs' source isn't public yet, and the command-line verifier is available on request. Earlier work, like the Lido proof and the first verifier contracts, is public at github.com/willow-network.
How do I get started?
Get an API key, then follow the quick start in the docs. For anything bigger, .