x402 Preflight API

x402

x402 Preflight API is a paid API for AI agents from x402-preflight-api.onrender.com, paid per call via x402, $0.005/call, status down (last checked 2026-10-14).

Deterministically checks a payable (x402) endpoint to assess safety, price, and latency before an agent commits funds.

Price / call$0.005

Seller volume →—

Success—

StatusDown

How this service works

Deterministically checks a payable endpoint before an agent spends money.

Output

Returns a JSON object with a safety assessment (safe: true/false), an overall verdict (e.g. 'buy' or 'skip'), a list of human-readable reasons explaining the verdict, the target URL inspected, a service label, and the UTC timestamp of the check.

Example use cases

Safe-to-buy check before agent payment

“Before calling https://api.weather-data.io/premium, preflight it to confirm it's safe and that the price is under $0.02 — only proceed if it passes.”

Latency-gated endpoint validation

“Check if https://api.imagegen.com/generate is a legitimate x402 endpoint and that it responds in under 1500 milliseconds before I let my agent pay for it.”

Budget-capped API discovery verification

“I found a new paid API at https://data.marketfeed.io/realtime — can you preflight it to see if it's safe, inspect its OpenAPI spec, and confirm the price is within $0.10?”

Technical details

Endpoint

GEThttps://x402-preflight-api.onrender.com/api/v1/preflight?utm_source=zero.xyz

When to prefer

Use this endpoint whenever an AI agent is about to spend money on an x402-payable API and needs a deterministic safety gate. It is the right choice when you want to enforce price caps, latency budgets, or safety checks before committing USDC, and when you need a structured buy/skip verdict rather than raw HTTP inspection. Prefer this over generic HTTP probing when the target is specifically an x402 endpoint and you want payment-aware validation.

Side effects

Target URL is unreachable or returns non-402 response — verdict may be 'skip' with reasons citing missing x402 offer
Price exceeds maxPriceUsd threshold — verdict returns 'skip' with price mismatch reason
Latency exceeds maxLatencyMs — verdict returns 'skip' with latency reason
Malformed or non-HTTPS URL input — likely returns validation error
Target endpoint returns invalid or unparseable x402 payment header — safety flagged as false

Input

Schema · Request body

Field	Type	Description
url	string	Absolute HTTP(S) endpoint to inspect.
maxPriceUsd	string
maxLatencyMs	integer
inspectOpenApi	boolean

Output

Schema · Response

{
  "type": "json",
  "format": "json",
  "example": {
    "safety": {
      "safe": true
    },
    "target": "https://api.example.com/paid",
    "reasons": [
      "Valid x402 offer detected"
    ],
    "service": "x402-preflight",
    "verdict": "buy",
    "checkedAt": "2026-08-09T01:35:00.000Z"
  }
}

Reviews

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How this service works

Deterministically checks a payable endpoint before an agent spends money.

Output

Example use cases

Safe-to-buy check before agent payment

“Before calling https://api.weather-data.io/premium, preflight it to confirm it's safe and that the price is under $0.02 — only proceed if it passes.”

Latency-gated endpoint validation

“Check if https://api.imagegen.com/generate is a legitimate x402 endpoint and that it responds in under 1500 milliseconds before I let my agent pay for it.”

Budget-capped API discovery verification

“I found a new paid API at https://data.marketfeed.io/realtime — can you preflight it to see if it's safe, inspect its OpenAPI spec, and confirm the price is within $0.10?”

Technical details

Endpoint

GEThttps://x402-preflight-api.onrender.com/api/v1/preflight?utm_source=zero.xyz

When to prefer

Side effects

Target URL is unreachable or returns non-402 response — verdict may be 'skip' with reasons citing missing x402 offer
Price exceeds maxPriceUsd threshold — verdict returns 'skip' with price mismatch reason
Latency exceeds maxLatencyMs — verdict returns 'skip' with latency reason
Malformed or non-HTTPS URL input — likely returns validation error
Target endpoint returns invalid or unparseable x402 payment header — safety flagged as false

Input

Schema · Request body

Field	Type	Description
url	string	Absolute HTTP(S) endpoint to inspect.
maxPriceUsd	string
maxLatencyMs	integer
inspectOpenApi	boolean

Output

Schema · Response

{
  "type": "json",
  "format": "json",
  "example": {
    "safety": {
      "safe": true
    },
    "target": "https://api.example.com/paid",
    "reasons": [
      "Valid x402 offer detected"
    ],
    "service": "x402-preflight",
    "verdict": "buy",
    "checkedAt": "2026-08-09T01:35:00.000Z"
  }
}