CORS Policy Checker API

API ID 14063

Give it a URL (and optionally the Origin to check) and it checks that server's CORS response headers (Access-Control-Allow-Origin, -Methods, -Headers, -Credentials, -Max-Age) using both a simple

224 ms avg response

API Documentation

Endpoints

Request
Checks the CORS response headers of the target URL with both a simple request and a preflight request and returns whether the origin is allowed plus any misconfiguration issues. Results are cached for 6 hours.
Endpoint ID: 34492
GET https://zylalabs.com/api/14063/cors+policy+checker+api/34492/check+url+cors+policy
INPUT PARAMETERS

Check URL CORS Policy — Endpoint Features

Object Description
url Required URL to check, including scheme (e.g. https://api.example.com)
origin Optional Origin to check with (defaults to https://example.com). Example: https://myapp.com

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

url
origin
API EXAMPLE RESPONSE
JSON
{
    "url": "https://api.github.com/",
    "origin": "https://myapp.com",
    "originIsDefault": false,
    "simpleRequest": {
        "statusCode": 403,
        "headers": {
            "access-control-allow-origin": "*",
            "access-control-expose-headers": "ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset, X-RateLimit-Used, X-RateLimit-Resource, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type, Deprecation, Sunset"
        }
    },
    "preflight": {
        "statusCode": 204,
        "headers": {
            "access-control-allow-origin": "*",
            "access-control-allow-methods": "GET, POST, PATCH, PUT, DELETE",
            "access-control-allow-headers": "Authorization, Content-Type, If-Match, If-Modified-Since, If-None-Match, If-Unmodified-Since, Accept-Encoding, X-GitHub-OTP, X-Requested-With, User-Agent, GraphQL-Features, X-Github-Next-Global-ID, X-GitHub-Api-Version, X-Fetch-Nonce, Copilot-Integration-Id, DD-CLIENT-TOKEN, X-Client-Application, X-Experiment-Commit-Agent-Version, Idempotency-Key",
            "access-control-expose-headers": "ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Used, X-RateLimit-Resource, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type, X-GitHub-SSO, X-GitHub-Request-Id, X-GitHub-Edge-Region, Deprecation, Sunset",
            "access-control-max-age": "86400",
            "vary": "Accept-Encoding, Accept, X-Requested-With"
        }
    },
    "issues": [],
    "cached": true
}
Check URL CORS Policy — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14063/cors+policy+checker+api/34492/check+url+cors+policy?url=https://api.github.com&origin=https://myapp.com' --header 'Authorization: Bearer YOUR_API_KEY' 


    

API Access Key & Authentication

After signing up, every developer is assigned a personal API access key, a unique combination of letters and digits provided to access to our API endpoint. To authenticate with the CORS Policy Checker API simply include your bearer token in the Authorization header.

Headers
Header Description
Authorization Required Should be Bearer access_key. See "Your API Access Key" above when you are subscribed.

No long-term commitment. Upgrade, downgrade, or cancel anytime. Free Trial includes up to 50 requests.

Starts at
$10,000/Year


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Overview

Give it a URL (and optionally the Origin to check) and it checks that server's CORS response headers (Access-Control-Allow-Origin, -Methods, -Headers, -Credentials, -Max-Age) using both a simple request and a preflight (OPTIONS) request, then returns structured JSON. Common CORS misconfigurations are flagged automatically in an issues array: a wildcard origin combined with Credentials true (invalid per the spec), missing Access-Control headers that make browser cross-origin calls fail, and a requested Origin that is not in the allowed list. Useful for API integration debugging, automated pre-deploy checks (CI), and checking whether a third-party API can be called from a browser. CORS is defined by the WHATWG Fetch Standard. If no Origin is given, a neutral probe (https://example.com) is used. The verdict accounts for servers that attach CORS headers to only one of the simple request or preflight responses, but because servers may respond differently per request method and headers, it does not cover every possible combination. Results are cached for 6 hours.

CORS Policy Checker API FAQs

The Check URL CORS Policy endpoint returns structured JSON data that includes the CORS response headers from both simple and preflight requests, along with a verdict on whether the origin is allowed and any identified misconfiguration issues.

Key fields in the response include "url" (the checked URL), "origin" (the origin being checked), "simpleRequest" and "preflight" (each containing status codes and headers), and "issues" (an array of identified CORS misconfigurations).

The response data is organized into a JSON object with top-level fields for the URL, origin, and two nested objects for simple and preflight requests, each containing status codes and headers, plus an issues array for misconfigurations.

The endpoint provides information on CORS response headers, including Access-Control-Allow-Origin, -Methods, -Headers, -Credentials, and -Max-Age, as well as any misconfiguration issues detected during the checks.

The primary parameter is the URL to check, and an optional "Origin" parameter can be provided to specify the origin being tested. If no origin is given, a default neutral probe is used.

Users can analyze the returned CORS headers to ensure their applications can make cross-origin requests successfully. The issues array helps identify and resolve common misconfigurations, improving API integration and deployment readiness.

Typical use cases include debugging API integrations, performing automated checks during CI/CD processes, and verifying if third-party APIs can be accessed from a browser, ensuring compliance with CORS policies.

Data accuracy is maintained by checking both simple and preflight requests, allowing the API to detect inconsistencies in CORS headers. Additionally, results are cached for 6 hours to ensure timely yet reliable information.

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