The simplest possible agent. Send a message with an x402 micropayment, get it echoed back with full payment diagnostics.
The x402 protocol adds a payment layer to HTTP. Echo Agent lets you test the full flow without building anything.
Send a POST to /echo with your message. No payment header yet.
Server returns 402 Payment Required with accepted tokens and price.
Your client signs an EIP-712 permit and retries with the PAYMENT-SIGNATURE header.
Payment is settled on-chain via the facilitator. Your message is echoed back with diagnostics.
The API runs on port 8402. All endpoints below are relative
to the API base URL.
Use the Python test client or generate a payment header for curl/Postman.