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x402 Payment Challenge Verifier
x402
x402 Payment Challenge Verifier is a paid API for AI agents from agentic-endpoints-testnet.oliver-835.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-12).
Fetches the live x402 payment challenge from a target endpoint and flags any drift in receiving address, network, or asset compared to prior observations
Price / call$0.003
Success—
StatusUnknown
How this service works
Before paying a stranger's x402 endpoint, read its live payment challenge and compare it against every previous observation. Flags a changed receiving address, network or asset as critical drift. Reports what the endpoint declares; it does not certify the operator.
Output
Returns the live x402 payment challenge data declared by the target endpoint, along with a drift report comparing it against the expected values you provided. Critical flags are raised for any mismatches in receiving address, network/chain, or asset. The service reports what the endpoint declares without certifying the operator.
Example use cases
Pre-payment address drift check
“Before my agent pays the x402 endpoint at https://partner-api.example.com/inference, verify its live payment challenge and check whether the pay-to address or network matches what I recorded last week: address 0xDEADBEEF1234, Base network, USDC. Warn me if anything changed.”
New vendor endpoint vetting
“I found a new x402 API at https://stranger-api.xyz/v1/compute and the listing says it pays to 0x9F8Cabc on eip155:8453 with a max price of $0.05. Can you read its live challenge and tell me if those details actually match before I trust it?”
Automated payment safety guard
“Before my workflow sends payment to https://data-feed.thirdparty.io/prices, fetch its x402 challenge and flag it as critical if the receiving address, asset, or chain is different from what I configured: pay_to 0xFEED1234CAFE, network base, asset USDC.”
Technical details
Endpoint
POSThttps://agentic-endpoints-testnet.oliver-835.workers.dev/x402/verify?utm_source=zero.xyzWhen to prefer
Use this endpoint whenever an AI agent or automated workflow is about to pay an x402-gated API, especially when the endpoint belongs to an unknown or third-party operator. It is the right choice when you want to detect address substitution attacks, verify chain/asset consistency, or enforce a max price cap before committing a payment. Prefer this over blind trust in directory listings when financial safety is a concern.
Side effects
- Private or loopback URLs are refused and not fetched
- Target endpoint is unreachable or returns a non-402 response
- Malformed URL input causes rejection
- No payment challenge returned if the endpoint does not implement x402
- Expected values not provided means no drift comparison is performed
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Public HTTP(S) URL of the paid endpoint. Private and loopback addresses are refused, not fetched. |
| expect | object | Optional. What you believe to be true, typically from a directory listing. Mismatches are reported so you can trust the live challenge over the listing. |
| method | string | Method used to provoke the challenge: POST (default), GET or HEAD |
Tags
x402
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