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Introduction to X402 Echo Merchant

The x402 Echo Merchant is a free, live x402-powered merchant you can use to test any x402 client end‑to‑end. It behaves like a real merchant: it advertises payment requirements, verifies your payment, settles it, and fulfills the request. The only difference is economic: every token you send is refunded immediately and PayAI covers the network fees. This gives you production‑like behavior with zero cost.

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At a glance

  • Live URL: https://x402.payai.network
  • Who it’s for: Developers building or validating x402 clients
  • What happens: You send a payment → the request is fulfilled → your tokens are refunded → fees are paid by PayAI

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Why use it

  • Fast iteration: Validate your x402 client integration without deploying your own merchant.
  • Zero cost: All tokens are refunded and PayAI pays on‑chain fees.
  • Realistic flow: Exercise discovery, verification, retry with X-PAYMENT, and settlement just like a production merchant.
  • Multi‑network coverage: Test on the networks supported by x402 without juggling faucets or balances.

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How it fits into the x402 flow

  1. Your client requests a protected resource at the Echo Merchant.
  2. The Echo Merchant responds with 402 Payment Required and payment requirements.
  3. Your client constructs a Payment Payload and retries with the X-PAYMENT header.
  4. The Echo Merchant verifies and settles the payment, then fulfills the request.
  5. The response includes X-PAYMENT-RESPONSE (base64 JSON) you can decode for details.
Use any of these examples and simply point the base URL to the Echo Merchant to validate your implementation.