Chainlink price feed reads for three pairs: ETH/USD and BTC/USD on Ethereum (chain 1) and MATIC/USD on Polygon (chain 137). POST /v1/price with {pair, chain_id} and get the latest answer, feed address and update time. Any other pair answers 400. Pay per request in USDC; no account, no API key.
| Network | Scheme | Amount | Pay To |
|---|---|---|---|
| Base | exact | $0.005000 USDC | 0xF732...B829 |