btc402: Bitcoin node data, paid per call or in sats
What it is. btc402 is a small, open service that runs on our own Bitcoin node. It sells two pieces of live Bitcoin mainnet data, the current block height and a fee estimate, to apps and AI agents.
Why. A lot of software needs a little trustworthy chain data without running a node. A pruned Bitcoin node validates every rule itself and needs about 10 GB instead of about 700 GB, which makes it cheap enough to run as infrastructure.
What it does.
- x402, pay per call. Ask without paying and you get HTTP 402 with the price, 0.001 USDC on Base. Retry with a signed payment and you get the answer plus a receipt.
- Lightning, recurring use. Create an API key, top it up with a BOLT11 invoice in sats, or buy a monthly plan. Each call costs 1 sat or comes out of the plan.
- The UnyKorn chain, registry. The offer, the prices and a hash of every payment are sent to the UnyKorn chain registry API as signed records, and every paid response carries an
X-UnyKorn-Recordreference. Records contain hashes only, never keys or payment secrets.
Status today (Oct 13, 2026).
- The node is a pruned Bitcoin Core 31.1 node and is still on its initial sync.
- The service runs on our own machine on localhost and is not open to the public yet. Unpaid calls correctly get HTTP 402.
- x402 is connected to the Coinbase CDP facilitator, and authentication with it is confirmed. No real paid call has gone through yet.
- The Lightning rail runs on phoenixd and creates real BOLT11 invoices. No payments have been received yet.
- The registry API for the UnyKorn chain is live at registry.unykorn.org. It stores HMAC-signed records: the offer, prices and hashes of payments. These records are kept in the registry API and are not on-chain writes yet. Anchoring them on the UnyKorn chain is the next step.
Built on Bitcoin Core (unmodified). This is not a fork. We run the official Bitcoin Core release without changes. Credit goes to bitcoin.org, bitcoincore.org and the Bitcoin Core contributors, and Bitcoin Core is MIT-licensed. What we added on top: the pruned-node deployment, the x402 per-call layer, the Lightning rail, the UnyKorn chain registry and a wallet helper script.
This is a data service. It is not financial advice, and it never holds customer funds.