CORS Header & Server Security Rule Builder
Generate production-ready Cross-Origin Resource Sharing rules for Express, Nginx, Next.js, and Apache.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. No data is ever transmitted across the network.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
How to Use CORS Header & Server Security Rule Builder
Enter allowed domain origins and enable credentials if needed.
Choose allowed HTTP methods and header types.
Copy or download the target Express, Nginx, Next.js, or Apache configuration.
Frequently Asked Questions
What is CORS preflight?
Preflight is an automated HTTP OPTIONS request sent by browsers before cross-origin requests to check server permissions.
Can I use wildcards with credentials?
No, W3C CORS security specifications prohibit Access-Control-Allow-Origin: * when Access-Control-Allow-Credentials is true.
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