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x402 Preflight Checker
x402
x402 Preflight Checker is a paid API for AI agents from email-preflight-api.vercel.app, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-13).
Inspects a live x402 v2 payment challenge before an agent commits to payment, verifying price, network, payee, resource binding, timeout, and Bazaar metadata without paying or forwarding credentials.
Price / call$0.003
Success—
StatusUnknown
How this service works
Pre-action check for AI agents: inspect an unfamiliar live x402 v2 challenge immediately before purchase. Verify price, network, payee, resource binding, timeout, and Bazaar metadata without paying the target or forwarding credentials. POST probes send only a fixed empty JSON object; callers cannot supply target request content.
Output
Returns structured details about the x402 v2 challenge: the required payment price and currency, target network, payee address, resource binding confirmation, challenge timeout, and any Bazaar metadata — all without triggering a payment or exposing caller credentials.
Example use cases
Safe agent purchase guard
“Before my agent pays for that x402 API, check the live payment challenge and tell me the exact price, what network it's on, and who the payee is — I want to confirm everything looks right before any USDC leaves my wallet.”
Unfamiliar x402 endpoint audit
“I found this x402-protected endpoint from an unknown provider — can you inspect its payment challenge and verify the price, resource binding, and Bazaar metadata without forwarding my credentials or actually paying?”
Timeout and expiry check
“My agent is about to call an x402 endpoint but I'm worried the challenge might expire — can you do a preflight probe to check the timeout and confirm the challenge is still valid before we proceed?”
Technical details
Endpoint
POSThttps://email-preflight-api.vercel.app/api/x402-preflight?utm_source=zero.xyzWhen to prefer
Use this endpoint whenever an AI agent is about to pay an unfamiliar or untrusted x402-protected resource and needs to verify payment terms, payee identity, and metadata before committing funds. It is specifically designed for the x402 v2 protocol and Bazaar marketplace context, making it the right choice over generic HTTP inspection tools when payment safety and protocol compliance are the concern.
Side effects
- Target URL unreachable or returns non-x402 response
- x402 challenge version mismatch (not v2)
- Challenge already expired at time of probe
- Malformed or missing Bazaar metadata fields
- Network timeout on preflight probe
- Target endpoint returns unexpected status code
Tags
x402
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