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x402 Endpoint Buyer Preflight
x402
x402 Endpoint Buyer Preflight is a paid API for AI agents from ai-data-marketplace-1042299154756.us-central1.run.app, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-20).
Probe a live x402-protected endpoint to validate its HTTP 402 challenge, payment requirements, and marketplace listing before authorizing payment.
Price / call$0.003
Success—
StatusUnknown
How this service works
Verify and lint a third-party x402 endpoint without paying it. Probe the live HTTP 402 challenge, validate x402 v2 and Base payment requirements, and check exact Coinbase Bazaar and 402index listing evidence before a buyer authorizes payment.
Output
Returns the parsed HTTP 402 challenge headers and body, x402 v2 protocol conformance results, Base network payment requirement details (token, amount, recipient), Coinbase Bazaar listing evidence, 402index listing presence, and any lint warnings or validation errors — all without forwarding payment credentials or executing a transaction.
Example use cases
Validate x402 API before agent payment
“I found an x402 API at https://some-marketplace-api.com/data and I want to make sure it's legit before my agent pays for it — can you probe it with a GET request and tell me if the 402 challenge is valid, what payment it requires, and whether it shows up on Coinbase Bazaar?”
Lint third-party endpoint for v2 compliance
“Can you check if https://thirdparty-api.io/premium-endpoint is properly x402 v2 compliant and accepts Base network USDC payments? Use a POST probe with an empty body and flag any issues before I whitelist it for my agent.”
Confirm 402index listing before budget approval
“Before I approve budget for my agent to call https://data-vendor.xyz/api/feed, probe it with a GET and confirm it's actually listed on 402index — I only want to authorize payment to endpoints with verified marketplace listings.”
Technical details
Endpoint
GEThttps://ai-data-marketplace-1042299154756.us-central1.run.app/api/v1/x402_endpoint_preflight?utm_source=zero.xyzWhen to prefer
Use this endpoint when an AI agent or buyer needs to vet an unknown or third-party x402-protected API before authorizing any payment. It is the correct choice when you need zero-cost pre-authorization verification, x402 v2 protocol linting, Base network compatibility checking, or marketplace listing confirmation. Prefer this over blindly calling a paid endpoint or over general HTTP inspection tools that lack x402-specific validation logic.
Side effects
- Target endpoint is not reachable or returns non-402 status — validation cannot proceed
- Endpoint returns a 402 but with malformed or missing x-payment-required headers — lint errors reported
- Endpoint is not listed on Coinbase Bazaar or 402index — listing evidence returns negative
- Network timeout when probing the live endpoint
- Request body forwarding rejected because it contains payment credentials — stripped and flagged
- Endpoint requires a payment method other than Base USDC — flagged as incompatible
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"success": true,
"decision": "payment_challenge_is_structurally_ready",
"discovery": {
"coinbase_bazaar": {
"checked": true,
"exact_match_count": 1
}
},
"ready_for_payment": true,
"payment_requirements": []
}
}Tags
x402
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