CORS Checker
Free online CORS checker. Scan any website or API to test Cross-Origin Resource Sharing configuration, detect dangerous origin reflection, verify credentials handling, and identify misconfigured CORS policies that expose your data to unauthorized access.
No https:// needed · Free · No credit card
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
1
Enter your API or website URL
2
We send requests with various Origin headers
3
CORS response headers are captured and analyzed
4
Dangerous patterns like origin reflection are detected
5
You receive a security assessment with recommendations
Security Checks Included
This tool runs the following security checks on your website
Frequently Asked Questions
What is a CORS checker?
A CORS checker is a free online tool that tests your website or API's Cross-Origin Resource Sharing configuration. It sends requests with various origins and analyzes the response headers to detect dangerous misconfigurations like origin reflection or overly permissive wildcard policies.
How do I test my CORS configuration?
Enter your website or API URL in the CORS checker above. We'll send cross-origin requests and analyze all Access-Control-* headers, checking for dangerous patterns and showing you exactly what needs to be fixed.
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 from reading your API responses.
What is origin reflection?
Origin reflection means echoing back whatever Origin header the browser sends in the Access-Control-Allow-Origin response. Combined with credentials, this allows any website to access your authenticated API data — a critical vulnerability that can lead to data theft.
Should I use Access-Control-Allow-Origin: *?
Wildcards are only safe for truly public APIs without authentication. Never use * with Access-Control-Allow-Credentials: true. Use an explicit allowlist of trusted origins for any authenticated endpoint.
Why is CORS misconfiguration dangerous?
Misconfigured CORS can allow malicious websites to make authenticated requests to your API using a logged-in victim's cookies, then read the response. This enables data theft, account takeover, and CSRF-like attacks even with HTTPS.
Is this CORS checker free?
Yes, our CORS checker is completely free. It tests 6 CORS-related headers and is part of SecScanner's free security toolkit that also checks SSL, security headers, DNS, cookies, and more.
Ready to Check Your Website?
Run a free security scan now and get instant results with actionable fix recommendations.
No https:// needed · Free · No credit card