CORS Checker

Test your Cross-Origin Resource Sharing configuration for security issues. Detect misconfigured CORS policies that could expose your API to unauthorized access.

What We Check

Access-Control-Allow-Origin testing

Credentials handling verification

Preflight request analysis

Exposed headers check

Origin reflection detection

Vary header verification

How It Works

Enter your API or website URL

We send requests with various Origin headers

CORS response headers are captured and analyzed

Dangerous patterns like origin reflection are detected

You receive a security assessment with recommendations

Security Checks Included

This tool runs the following security checks on your website

Access-Control-Allow-Origin Access-Control-Allow-Credentials Access-Control-Allow-Headers Access-Control-Expose-Headers Access-Control-Max-Age Vary: Origin header (CORS caching)

Frequently Asked Questions

What is CORS?

CORS (Cross-Origin Resource Sharing) is a browser security feature that controls which websites can access your resources. It prevents unauthorized cross-origin requests.

Why is CORS security important?

Misconfigured CORS can allow malicious websites to steal data from your API using a user's credentials. This is a common source of data breaches.

What is origin reflection?

Origin reflection means echoing back whatever Origin header the browser sends. Combined with credentials, this allows any website to access your data - a critical vulnerability.

Should I use Access-Control-Allow-Origin: *?

Wildcards are only safe for truly public APIs without authentication. Never use * with credentials. Use an explicit allowlist of trusted origins instead.

Ready to Check Your Website?

Run a free security scan now and get instant results with actionable fix recommendations.