Funding (USDC on Base)

How much to keep

Less than you'd think. x402 settles via an EIP-3009 TransferWithAuthorization, which is gasless— there's no ETH to keep for gas. You only need enough USDC to cover the calls you'll make: a balance at or above your per-call cap is enough to start, and a few dollars covers a lot of typical calls (most are fractions of a cent).

Getting USDC onto Base

The common routes, in rough order of convenience:

• Withdraw from an exchange that supports the Base network — pick USDC, choose Base as the network, and send it to your wallet address.
• Bridge from Ethereum (or another chain)using Base's official bridge or any reputable bridge that supports USDC on Base.
• Already have USDC on Base elsewhere? Just send it to your wallet address. On the dashboard, your account shows the address and a QR to scan from a phone wallet.

Always confirm you're sending USDC on the Basenetwork — funds sent on the wrong network won't arrive.

Testnet (Base Sepolia)

To try things without real money, use Base Sepolia and a Base Sepolia faucet for test USDC. Select Base Sepolia in your wallet (or the embedded-wallet flow), and point your SDK config at the base-sepolia network.

Supported networks

x402 settlement runs on Base mainnet and Base Sepolia (testnet). USDC is the settlement token on both.

If you run dry

A call whose quoted price exceeds your available balance simply doesn't settle — the payment fails rather than overdrawing, and the agent gets the error back. Top up the wallet and it resumes; nothing is queued or owed. The dashboard surfaces a low-balance nudge so you see it coming.

Next: the quickstart makes your first paid call, and create an account sets up a wallet with just an email.