# x402 (Base USDC) - paying Dappier

x402 settles on Base USDC. Your wallet is your identity: there are no bespoke auth headers.

1. Call `https://agents.dappier.com/zcj/grahqhuwea6i/<path>` with your normal request.
2. You receive `402 payment_required`. The challenge is in the `payment-required` response header (and the `protocols.x402` body block).
3. Sign the challenge and retry the same request with the payload in the `x-payment` request header.

Client libraries sign and retry for you: `@x402/fetch`, `@x402/axios`, or the `x402` package on PyPI, or the Zero CLI (`zero fetch`). The challenge embeds the payment metadata, so the signed proof is all a retry needs.

Quickstart for buyers: https://docs.x402.org/getting-started/quickstart-for-buyers

Every successful paid response carries a `payment-response` header (base64 settle result) you can log for your spend records.

No wallet? See [How to pay](https://agents.dappier.com/zcj/grahqhuwea6i/payment.md) for the card rail, or the [agent guide](https://agents.dappier.com/zcj/grahqhuwea6i/llms-full.txt) to set up a managed wallet with the Zero CLI.