Base Sepolia
Use Base Sepolia testnet for the documented AgentRouter purchase flow. Fund your agent wallet with test tokens, not real funds. The model catalog displays real inference prices.
Choose the MetaMask or Coinbase guide for wallet setup and the runnable purchase steps. Mainnet documentation is work in progress, not an alternative purchase procedure.
Network details
| Setting | Value |
|---|---|
| Network | Base Sepolia |
| Chain ID | 84532 |
| x402 network | eip155:84532 |
| RPC | https://sepolia.base.org |
| Explorer | Base Sepolia explorer |
| Payment asset | Base Sepolia test USDC |
| USDC contract | 0x036CbD53842c5426634e7929541eC2318f3dCF7e |
Use Base Sepolia only, even if your wallet also lists mainnets. Keep USDC and any test ETH on this network.
Get test USDC
First obtain your agent wallet's public address: MetaMask wallet check or Coinbase address. For MetaMask, use the separate agent wallet, not your personal phone wallet.
With the wallet owner's approval, open the Circle faucet.
- Select USDC and Base Sepolia.
- Paste your wallet's EVM address.
- Click Send 20 USDC and wait for confirmation.
Already have Base Sepolia test USDC in another wallet? You can transfer it to this address instead. Use test tokens only; do not buy or send real funds for this setup.
If Circle is unavailable, follow the UI (CDP Portal) section of Coinbase's faucet instructions. Sign in to a Coinbase Developer Platform account, open Faucets, select Base Sepolia and USDC, paste the same EVM address, and click Claim. This requires a CDP developer account, separate from the wallet's email login.
After confirmation, check the MetaMask balance or check the Coinbase balance. In MetaMask, unpriced and totalValue: 0 can reflect missing testnet prices, not an empty wallet. Read the token's amount and network before funding again.
Gas and test ETH
The documented USDC x402 flow has the facilitator submit the settlement transaction and pay its gas. A zero-ETH purchase was not independently tested in the supplied Coinbase walkthrough; its successful purchase does not prove that case. See who pays x402 gas.
Only if another transaction requires unsponsored gas, follow the optional test ETH instructions. Use the same public EVM address and Base Sepolia network. Never provide a seed phrase or private key to a faucet.
Wallet checks
- MetaMask: check authentication, wallet and allowed chains. A zero daily USD limit does not guarantee zero x402 spending: signatures are excluded from that limit. Obtain the wallet owner's spending approval.
- Coinbase: check smart-account deployment. This purchase path requires an already-deployed account. Stop on NOT DEPLOYED, CHECK FAILED, or an error. Funding the address alone is not proof of deployment.
Purchase and settlement
Read the offer with MetaMask or Coinbase before authorizing payment. The documented offer uses exact, network eip155:84532, the USDC contract above and amount 1000000 (1 test USDC). Inspect the current offer and recipient; stop if the terms differ from what you intend to buy. This is access credit, not the price of one model request.
Follow the MetaMask purchase step or Coinbase purchase step once, with the owner's approval. Keep the response, receipt and bearer key private.
Check the receipt's transaction on the Base Sepolia explorer: it should show a successful USDC transfer from your agent wallet to the recipient in the offer. If payment or delivery is uncertain, stop and inspect the saved result. Do not repeat a payment to recover a key.
Use your key
With a purchased key, follow the shared Discover models, OpenAI-compatible API or Anthropic-compatible API guide. The post-purchase steps are the same for both wallets.