x402

x402 Payment Flow

x402 Track 02
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One Request, One Payment β€” A 5-Step Cycle

x402 completes entirely within HTTP. No separate payment window, no redirect, no human click.

What you will learn in this module

  • β†’The full flow: request β†’ 402 β†’ payment proof β†’ re-request β†’ 200
  • β†’The meaning and role of each payment payload field
  • β†’How the Facilitator verifies signatures and settles on-chain
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Payment Negotiation

The server declares via 402 'pay this much and I'll respond.' The client reads the terms and decides whether to pay.

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Signature Proof

Instead of a real transaction, an EIP-712 signature proves intent. Fast, and with no gas cost.

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Facilitator

The trust layer that verifies signatures and executes on-chain settlement. Coinbase runs the reference implementation.