USDC
Gateway Nanopayments supports gas-free USDC payments only on the EVM blockchains in the Gateway supported blockchains reference.EURC and cirBTC
Nanopayments also supports EURC and cirBTC on a subset of those blockchains. For the differences from USDC, see Use EURC and cirBTC with Gateway.Specifying a blockchain
Use theSupportedChainName value from the Gateway supported blockchains table
when initializing GatewayClient or configuring the SDK:
When using
GatewayClient, deposits and payments are scoped to the blockchain
you configure on the client. If you want to pay on Base, initialize the client
for Base and deposit there. To avoid long deposit wait times, use the
Bridge capability in Arc App Kits to
bridge your USDC to a fast-finality blockchain before depositing. The
Fast deposits section
offers third-party alternatives for faster deposits.Contract addresses
If you are constructing EIP-712 signatures manually (without the SDK), you need the contract addresses for your target chain:- GatewayWallet address (used as
verifyingContractin the EIP-712 domain): EVM contract addresses - USDC token address (used as the
assetin payment requirements): USDC contract addresses
CHAIN_CONFIGS constant provides these values programmatically. See
the SDK reference for
details.
Testnet faucets
To test nanopayments, you need testnet USDC and native gas tokens:- Circle Faucet: testnet USDC for supported testnet blockchains
- For native gas tokens (required for onchain deposit transactions), use the blockchain-specific faucets listed on each testnet’s documentation site