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AgentIndex x402 Echo
x402
AgentIndex x402 Echo is a paid API for AI agents from x402.agentindex.world, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).
Validates x402 micropayment settlement by echoing the request back with payment confirmation details after a $0.000001 USDC payment on Base.
Price / call$0.001
Success—
StatusUnknown
How this service works
Cheapest possible Base-mainnet x402 conformance call: settle $0.001 of USDC and receive payer identity, request echo and receipt. Built for agents testing wallets, Payment-Signature, facilitators and settlement. Try GET /x402-echo/sample.
Output
Returns a JSON object confirming settlement with: ok (boolean), payer wallet address, network identifier (eip155:8453 for Base), purpose string, echoed request object, price in USDC (0.000001), atomic price in USDC units, and the full x402 payment receipt.
Example use cases
Verify x402 integration before deployment
“Run an echo test against the AgentIndex x402 endpoint with message 'pre-deploy-check' so I can confirm the payment settlement and receipt flow is working before I go live.”
Debug payer address in payment receipt
“Hit the x402 echo endpoint with a GET and the message 'debug-wallet' — I need to see the payer address and x402_receipt fields that come back after settlement to verify my wallet is being recognized correctly.”
Cheapest possible mainnet payment test
“Do the cheapest possible real mainnet x402 payment test on Base using the AgentIndex echo endpoint — I just want to confirm $0.000001 USDC actually settles and returns an ok:true response.”
Technical details
Endpoint
GEThttps://x402.agentindex.world/x402-echo?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to verify that your x402 micropayment integration is working end-to-end on Base mainnet at the absolute minimum cost ($0.000001 USDC). It is the canonical conformance test for the AgentIndex x402 protocol stack. Prefer this over other echo or health-check endpoints when you specifically need to confirm payment settlement, receipt generation, and payer address recognition in a single call.
Side effects
- Payment not settled — returns 402 if USDC micropayment is not included or fails
- Invalid method — only GET, HEAD, DELETE are accepted
- Malformed queryParams — unrecognized fields rejected due to additionalProperties:false
- Insufficient balance — agent wallet lacks USDC on Base
- Network mismatch — payment sent on wrong chain returns settlement error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"payer": "0xb3F32bdfe8D07825BC0D7387295aB1D7559BA69d",
"network": "eip155:8453",
"purpose": "x402-mainnet-conformance",
"request": {
"echo": {
"hello": "agent"
},
"method": "POST"
},
"price_usdc": 0.001,
"price_atomic_usdc": "1000"
}
}Tags
x402
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