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Documentation Index

Fetch the complete documentation index at: https://developers.circle.com/llms.txt

Use this file to discover all available pages before exploring further.

Nanopayments supports gas-free USDC payments on all EVM blockchains listed in the Gateway supported blockchains table where the Nanopayments column is marked Yes. Use the SupportedChainName value from the table when initializing GatewayClient or configuring the SDK: 
const client = new GatewayClient({
  chain: "base", // SupportedChainName from the supported blockchains table
  privateKey: "0x...",
});
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 Arc App Kit’s Bridge Kit to bridge your USDC to a fast-finality blockchain before depositing. The Fast deposits section offers third-party alternatives for faster deposits.

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Contract addresses

If you are constructing EIP-712 signatures manually (without the SDK), you need the contract addresses for your target chain: The SDK’s CHAIN_CONFIGS constant provides these values programmatically. See the SDK reference for details.

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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