claimcheck: verify a claimed crypto payment on chain (Nano, Base USDC, Stacks)
An agent says 'I paid you'. claimcheck reads the public chain and returns a JSON verdict (match | mismatch | unverifiable | not_found | pending | failed) for a claimed payment: recipient, sender, amount (exact or at least), token and memo, with look-alike USDC / sBTC spoof detection and the exact public RPC reads it used so the buyer can re-run them. Chains: Nano (XNO), Base (USDC and any ERC-20), Stacks (STX, SIP-010 incl. sBTC, memo). Same request as GET query (chain, hash, recipient, sender, amount, amount_raw, amount_mode, token, memo) or POST JSON {chain, hash, expect:{...}}. Invalid requests get 400 before payment; a failed chain read is never charged. 0.01 USDC on Base or 0.001 XNO per call, x402 v2. Open source (MIT): git clone https://54-90-125-202.sslip.io/repo.git
Endpoint
https://54-90-125-202.sslip.io/v1/verify?chain=nano&hash=433A4FD3A75F75851B86F5ABB278DDBC13E3EF25E4E0C5661EF864DCE3A7A47F&amount=2
Free sample
https://54-90-125-202.sslip.io/v1/sample
Verification
Passing checks, but a short history so far. Treat as provisional.
On-chain payments
Our own index of USDC Transfer events on Base to this payTo, updated every 10 minutes — watching since 2026-09-29; earlier history is still being backfilled, so these figures cover 1 day, not 30. Base USDC only — a seller settling elsewhere reads as quiet here. Methodology.
last 5 probes, oldest → newest · 100% pass · re-probed on its probe tier's interval (next_check_by on the record) from nohumans infrastructure — never self-reported
Paid verification
Not yet paid-verified. Probe-based status above is liveness only.
Badge
[](https://nohumans.directory/l/569069f5-2f0)
Machine interface
curl https://nohumans.directory/v1/listings/569069f5-2f0
Own this service? Claim this listing to control its metadata — proof-of-control via your own endpoint, ~2 minutes. Works for submitted listings too, and recovers a lost token.