Free CORS Policy Checker
Validate Access-Control headers, credentials safety, and simulate preflight behavior.
Fix misconfigurations like wildcard with credentials and missing Vary: Origin.
- ACAO configuration
- Preflight simulation
- Credentials safety
"Barrion's security scanning has helped us implement best security practices efficiently, saving us countless hours."
Sarah Chen
Head of Security
"We identified and fixed critical vulnerabilities before our platform launch, saving us from potential data breaches."
Marcus Anderson
CTO
"Barrion gives us peace of mind, knowing we're notified of any security issues. Exactly what our team needed."
Oskar Nilsson
Tech Lead
Scan in three simple steps
Fast, safe, non-intrusive checks with actionable results.
Start scan
Enter your URL, and click the start scan button to begin.
Scan runs
Barrion performs passive, read-only security checks with minimal site impact.
View results
See security findings with prioritized, actionable recommendations.
What is CORS?
Cross‑Origin Resource Sharing (CORS) controls which origins can read your API responses in browsers. Correct configuration prevents data exfiltration while allowing legitimate cross‑site apps.
Why CORS matters
A lax policy can expose private data to attacker-controlled origins. Overly strict settings break legitimate clients. The goal is least‑privilege, origin‑scoped access.
What this checker validates
- ACAO/ACAC/ACAH/ACEH values and consistency
- Credentials with wildcard origin (disallowed)
- Preflight handling (methods/headers) and Vary: Origin
- Max‑Age and exposure of sensitive headers
How to fix common failures
- When using credentials, set ACAO to the specific request origin, not "*"
- Return Vary: Origin so caches keep responses per origin
- Limit ACEH to required headers only
- Whitelist only necessary methods in preflight
Tool-specific questions
Can I use * with credentials?
Do I need Vary: Origin?
Should I expose Authorization?
How do I debug preflight failures?
Why Choose Barrion?
Real-Time Results
Instant security analysis with detailed reports, giving you an immediate security overview
Comprehensive Checks
Multiple best-practice security checks in a single scan, for broad coverage
Actionable and Effective
Clear recommendations for fixes, helping you improve your security quickly and effectively
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