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apiacre.com x402 Preflight Checker
x402
apiacre.com x402 Preflight Checker is a paid API for AI agents from apiacre.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-15).
Probes a public API endpoint to assess its x402 payment protocol compliance, returning a grade, protocol evidence, and remediation steps — without paying.
Price / call$0.05
Success—
StatusUnknown
How this service works
Probe a public endpoint without paying, grade its x402 v2 challenge, check exact-host x402-list presence and traction, and optionally rank licensed market matches with buyer-concentration caveats.
Output
Returns an x402 v2 compliance grade (e.g. pass/fail/partial), protocol evidence observed from the endpoint's response (headers, status codes, payment details), and actionable remediation steps describing what needs to be added or corrected to achieve full compliance.
Example use cases
Pre-launch x402 compliance audit
“I'm about to launch my paid API and I want to make sure it's fully x402 v2 compliant — can you run a preflight check on https://api.myproject.com/data and give me the compliance grade and a list of things I need to fix?”
Debugging a broken x402 payment wall
“My x402 payment wall at https://api.coolservice.io/generate doesn't seem to be working for clients — can you probe it and show me what protocol evidence is present or missing so I can figure out what's wrong?”
Third-party x402 integration check
“I'm thinking of integrating with https://api.thirdparty.xyz/v1/results as a paid data source — can you do an x402 preflight on it and tell me if it properly supports the protocol before I build the integration?”
Technical details
Endpoint
POSThttps://apiacre.com/v1/developer/x402-preflightWhen to prefer
Use this endpoint when you need to validate that a public API correctly implements the x402 payment protocol — especially before launching a paid API, integrating a third-party x402 service, or debugging why an x402 payment wall isn't working. It is the only known dedicated x402 compliance grading tool and provides both evidence and remediation, making it superior to manual header inspection.
Side effects
- Target endpoint is unreachable or times out — returns an error with no grade
- Endpoint requires authentication before returning x402 responses — may produce misleading results
- Non-public or firewalled endpoints cannot be probed
- Malformed URL input returns a validation error
- Target server returns unexpected response format that cannot be evaluated
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | |
| body | — | |
| method | string | |
| market_limit | integer | |
| market_query | — |
Output
Schema · Response
{
"type": "json",
"example": {
"data": {
"url": "https://apiacre.com/v1/developer/openapi-audit",
"grade": "A",
"score": 100,
"checks": [
{
"id": "http_402",
"passed": true,
"message": "Return HTTP 402 before payment.",
"severity": "high"
}
],
"method": "POST",
"payment": {
"scheme": "exact",
"network": "eip155:8453",
"version": 2,
"acceptsCount": 1
},
"finalUrl": "https://apiacre.com/v1/developer/openapi-audit",
"checkedAt": "2026-08-09T00:00:00+00:00",
"compliant": true,
"elapsedMs": 128,
"statusCode": 402,
"limitations": "One unpaid target request only; no payment is signed and ...",
"remediation": [],
"gradeVersion": "apiacre-x402-preflight/1",
"directoryEvidence": {
"market": {
"query": "audit",
"status": "ok",
"returned": 1,
"totalMatches": 31
},
"source": {
"url": "https://x402-list.com",
"name": "x402 List",
"apiUrl": "https://x402-list.com/api/v1/services",
"documentationUrl": "https://x402-list.com/api"
},
"target": {
"status": "matched",
"hostname": "apiacre.com",
"matchCount": 1,
"matchMethod": "exact_host"
},
"version": "apiacre-x402-directory-evidence/1"
}
},
"meta": {
"cached": false,
"sources": [],
"warnings": [],
"duration_ms": 42,
"next_actions": []
},
"service": "developer.x402-preflight",
"version": "1",
"request_id": "018f1f54-7f38-7ba2-8dc3-5f90272d9f1a"
}
}Tags
x402
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