Circle

Developer wallets, CCTP, Gateway, nanopayments, contracts, Mint, USDC/EURC.

CIRCLE_API_KEY talks to api.circle.com. CIRCLE_MINT_API_KEY talks to Circle Mint (api-sandbox.circle.com in sandbox). Do not mix keys.

Group	Actions
Wallets	Wallet sets, wallets, balances, transfers, sign typed data
CCTP V2	Deposit-for-burn, Iris attestation, receive/mint, domains
Gateway	Balances, transfer attestation
Nanopayments	Deposit, balance, x402 check/pay/settle, agent discovery, withdraw
Contracts	Import, deploy bytecode/template, monitors, logs
USDC / EURC	Lookup, balance, transfer, approve. Arc native USDC is 18-dec; ERC-20 is 6-dec
Mint	Ping, balances, transfers, payment intents, payouts. Wires need confirmDestructive=yes