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x402 Doctor – Deep Preflight Check
x402
x402 Doctor – Deep Preflight Check is a paid API for AI agents from x402-doctor.fizzl.eu, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).
Performs a comprehensive pre-payment analysis of an x402 endpoint, returning a pay/no-pay verdict, 30-day reliability history, seller reputation across endpoints, domain stability checks, and full diagnostics — without ever paying the endpoint.
Price / call$0.01
Success—
StatusUnknown
How this service works
Should my agent pay this expensive x402 endpoint? The pre-payment verdict plus the full diagnosis, the 30-day history per day, how reliable the seller's other endpoints are and whether the endpoint moved domains. Never pays the endpoint.
Output
Returns a structured verdict object including: a top-level verdict (go/caution/no_go), a safe_to_pay boolean, a human-readable summary, an array of per-payment-option details (network, asset, USD price, payability problems), a list of reasons driving the verdict, a 30-day daily history of endpoint status, seller statistics (total resources, unreliable count, payable ratio), domain stability checks, and a cached flag indicating whether the result was served from cache.
Example use cases
Pre-pay safety check for expensive endpoint
“I'm about to call an x402 endpoint at https://premium-data.example.com/prices that costs $0.10 per call — can you do a deep preflight check on it using GET and a $0.10 budget cap and tell me if it's a go, caution, or no-go before I spend anything?”
Seller reputation research before agent deployment
“We're integrating an x402 API at https://ai-tools.example.com/summarize into our production agent — do a deep preflight on it and tell me how reliable the seller is across all their endpoints and whether the domain has moved recently.”
Budget-constrained verdict for autonomous agent
“My agent wants to call https://weather-x402.example.com/forecast via GET, but our per-call budget is $0.02 — run a deep preflight check and tell me whether it comes back as go or no_go given that budget, plus show me the 30-day daily reliability history.”
Technical details
Endpoint
GEThttps://x402-doctor.fizzl.eu/api/v1/preflight/deep?utm_source=zero.xyzWhen to prefer
Use this endpoint when your agent is about to pay an x402 endpoint that is expensive (e.g. >$0.01), unfamiliar, or mission-critical, and you want a full deep analysis including 30-day history, seller reputation across all their endpoints, and domain movement checks. Prefer it over the lightweight single-check endpoint when you need the historical trend data and seller-level trust signals, not just a one-shot verdict. Choose it over the batch endpoint when you need the richest possible data on a single URL rather than quick verdicts across many URLs.
Side effects
- Target URL is unreachable — verdict returns 'unreachable' status with no payment options
- URL parameter missing or malformed — API returns validation error
- Endpoint is not an x402 endpoint — diagnosis returns unknown status with explanation
- Budget (max_usd) is below all available payment options — verdict is forced no_go
- Network CAIP-2 identifier is invalid — API returns parameter error
- Target endpoint has no history yet — history array returns empty or unknown entries
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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