Live trend signals for up to 10 assets in one call, flat price regardless of count. Pass ?assets=btc,eth,... from: btc,eth,sol,xrp,doge,ada,avax,link,dot,ltc,bch,uni,aave,xlm,hbar,shib,sui,near,atom,fil. Errors (before payment): 400 missing/unsupported/too many assets.
Use before paying any x402 invoice: decodes a base64 PAYMENT-REQUIRED header (query ?header= or JSON body {header}) and checks scheme exact, Base mainnet, Base USDC asset, payTo (EOA/contract/EIP-7702), human amount, timeout; returns verdict ok/warn/fail with reasons. Errors: 400 invalid header. Read-only; never signs or pays.
Check an x402 settlement on Base (chain 8453): tx exists/succeeded, USDC Transfer and AuthorizationUsed events (from, to, amount), confirmations. Pass ?tx=0x... Errors: 400 invalid tx hash. Read-only.