Stablecoin Verifier API — Pay Per Call with USDC on Base

🔧

Verify a stablecoin: issuer identity, GENIUS Act qualification status, and latest reserve attestation. Resolves the token from chain+address, a known symbol, or a tx hash. Free preview available. Part of the x402 Gateway — $0.005 per call, settled in USDC on Base. No accounts, no API keys: agents pay per request via the x402 protocol.

How payment works

Send a POST to https://x402.freeq.one/tools/verify_stablecoin without a payment header and the API replies 402 Payment Required with an x402 challenge (payTo address, USDC amount, Base network). A paying agent signs the USDC payment and retries with the PAYMENT-SIGNATURE header (base64 JSON payment payload) — settlement is verified on-chain in seconds and the API response returns with a PAYMENT-RESPONSE receipt header.

Example call

curl -X POST https://x402.freeq.one/tools/verify_stablecoin \
  -H "Content-Type: application/json" \
  -d '{"chain": "base", "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"}'

Browse every pay-per-call API on the all APIs page, or inspect the machine-readable service card and OpenAPI spec.