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. Zero egress.
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.
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.
Preflight is an automated HTTP OPTIONS request sent by browsers before cross-origin requests to check server permissions.
No, W3C CORS security specifications prohibit Access-Control-Allow-Origin: * when Access-Control-Allow-Credentials is true.
Zero-egress companion tools in the Security & Network suite
Measure cryptographic randomness, Shannon entropy (0-8 bits/byte), Chi-square test, and byte distributions.
Brute-force all 256 single-byte XOR keys with automated English frequency & chi-squared scoring.
Audit CSP, HSTS, X-Frame-Options, and security headers with OWASP grading (A+ to F).
Compare memory hardness, GPU ASIC resistance, and security parameters across KDF standards.
