Forest Web CORS Preflight Inspector

x402

Forest Web CORS Preflight Inspector is a paid API for AI agents from http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-20).

Sends a single CORS OPTIONS preflight request to a public URL and normalizes the Access-Control-Allow-* response into structured origin, method, and header permission decisions.

Price / call$0.002

Seller volume →—

Success—

StatusUnknown

How this service works

Machine-readable contract for active Forest paid capabilities. Unsigned paid calls return HTTP 402 with a PAYMENT-REQUIRED x402 challenge.

Output

Returns a normalized breakdown of the CORS preflight response: whether the target URL allows the specified origin, which HTTP methods are permitted, which request headers are allowed, and the raw Access-Control-Allow-* header values observed. The result reflects only what the server declared in the OPTIONS response at the exact URL — no redirects are followed and no cookies or credentials are sent.

Example use cases

Verify third-party API CORS policy

“I want to call https://api.openweathermap.org/data/2.5/weather from my web app at https://myapp.com — can you do a CORS preflight check to see if it allows GET requests with an Authorization header?”

Debug cross-origin fetch failure

“My frontend at https://dashboard.acme.com is getting blocked when trying to POST to https://api.partner.com/submit with Content-Type headers — can you preflight that URL for my origin and tell me exactly what CORS rules it declares?”

Audit public API before integration

“Before I integrate https://public-data-api.gov/records into my browser app at https://explorer.mysite.com, can you check what methods and headers it allows via CORS so I know what my requests can include?”

Technical details

Endpoint

POSThttps://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/cors/preflight?utm_source=zero.xyz

When to prefer

Choose this endpoint when you need a lightweight, non-invasive check of a URL's CORS policy before attempting a browser-side cross-origin fetch. It is ideal for pre-integration audits, debugging CORS errors, or validating that a third-party API will accept requests from a specific origin with particular methods and headers. It is not suitable when you need to follow redirects, test credentialed (cookie/Authorization) requests, verify actual resource responses, or execute JavaScript-dependent behavior.

Side effects

Target URL is unreachable or returns a network error — no CORS data returned
Server does not respond to OPTIONS requests — may indicate CORS is not supported
Redirect encountered — Forest does not follow redirects, so the CORS state of the final destination is not reported
Malformed or missing Access-Control-Allow-* headers — normalized result may show denial or undefined policy
URL does not match required http/https pattern — request rejected with validation error
Requested headers list exceeds 20 items — input rejected

Input

Schema · Request body

Field	Type	Description
url	string	Public HTTP(S) URL to inspect, resolve, or compare.
origin	string	Public origin value used to scope this lookup.
requested_method	string	Public requested method value used to scope this lookup.
requested_headers	array	Public requested headers value used to scope this lookup.

Output

Schema · Response

{
  "type": "json",
  "example": {
    "ok": true,
    "data": {
      "scope": "observed_noncredentialed_cors_preflight_only",
      "status": 100,
      "blockers": [],
      "warnings": [],
      "final_url": "example",
      "allowed_origin": "example",
      "method_allowed": false,
      "origin_allowed": false,
      "redirect_count": 0,
      "allowed_headers": [],
      "allowed_methods": [],
      "headers_allowed": false,
      "preflight_passes": false,
      "credentials_allowed": false,
      "provider_request_count": 1
    },
    "meta": {
      "cache": "miss",
      "provider": "safe-http-options",
      "checked_at": "2026-01-01T00:00:00.000Z",
      "duration_ms": 0
    },
    "version": "1",
    "capability": "cors.preflight"
  }
}

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