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x402 Doctor Preflight Check
x402
x402 Doctor Preflight Check is a paid API for AI agents from x402-doctor.onrender.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-10).
Validates an x402 payment endpoint before paying it, returning a go/caution/no_go verdict with the recommended payment option and detailed reasons
Price / call$0.001
Success—
StatusUnknown
How this service works
Is this x402 endpoint safe to pay? Check it before your AI agent pays: go / caution / no_go, the recommended payment option, and why (payment would fail, over your budget, price above advertised, not HTTPS, unknown token). Never pays the endpoint. Cached 10 min.
Output
Returns a verdict ('go', 'caution', or 'no_go'), a safe_to_pay boolean, a human-readable summary, a recommended payment option index, an array of payment options (each with USD cost, network, token symbol, pay-to address, and a list of problems), and a reasons array with severity levels ('no_go', 'caution', 'info') and machine-readable codes explaining the decision. Results are cached for 10 minutes.
Example use cases
Budget guard before agent pays API
“Check whether the x402 endpoint at https://api.example.com/weather is safe to pay — my max budget per call is $0.02 and I want to pay on Base (eip155:8453). Give me a go or no-go before my agent sends any money.”
Spot-check unknown paid endpoint
“I found a new x402 API at https://unknown-service.io/summarize and I'm not sure it's legit. Can you run a preflight check on it with a GET request and tell me if it's using HTTPS, what token it wants, and whether I should trust it?”
Verify price matches advertised rate
“Someone told me an x402 endpoint at https://data-provider.io/prices charges $0.001 per call, but I want to confirm before I integrate it. Can you do a preflight check and flag it if the actual price is higher than advertised?”
Technical details
Endpoint
GEThttps://x402-doctor.onrender.com/api/v1/preflight?utm_source=zero.xyzWhen to prefer
Use this endpoint whenever an AI agent is about to make a payment to an x402-enabled API and needs a safety check first — especially when the endpoint is unfamiliar, budget constraints matter, or you need to confirm token/network compatibility before committing funds. It is the right choice when you want a non-paying diagnostic that surfaces price mismatches, HTTPS issues, and unknown tokens before any transaction occurs. Prefer it over blindly calling the target endpoint when operating in automated pipelines where a bad payment could waste funds or expose the agent to fraudulent endpoints.
Side effects
- Target URL is unreachable or returns non-402 status — endpoint reports it cannot inspect the payment challenge
- Target endpoint uses an unknown or unsupported token — flagged as 'unknown token' reason with no_go verdict
- Budget (max_usd) is below the endpoint's price — verdict becomes no_go with over-budget reason
- Endpoint is not served over HTTPS — flagged as a no_go safety issue
- Malformed or missing x402 payment headers at the target — diagnosis shows format errors in reasons
- x402 Doctor itself may be temporarily unavailable on the Render free tier (cold start latency or downtime)
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"url": "https://ichimoku-signal.onrender.com/signal/BTC-USDT",
"cached": false,
"method": "GET",
"options": [
{
"usd": 0.02,
"index": 0,
"amount": "20000",
"pay_to": "0x6B0F4651eD42893ab58139938175E4a69f175F25",
"network": "eip155:8453",
"payable": true,
"problems": [],
"asset_symbol": "USDC",
"network_name": "Base"
}
],
"reasons": [],
"signals": {
"https": true,
"advertised_price_usd": 0.02,
"listed_in_cdp_bazaar": false
},
"summary": "OK to pay: $0.02 on Base.",
"verdict": "go",
"checked_at": "2026-09-23T17:00:00.000Z",
"safe_to_pay": true,
"recommended_option": 0
}
}Tags
x402
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