Run a real CORS preflight from your browser — a cross-origin request that shows whether an endpoint allows it, with the exact server headers to confirm.
Content reviewed October 2026 · About Toolzum
Generate correct CORS headers — Access-Control-Allow-Origin, methods, headers, credentials. Fix preflight failures with exact syntax — local generation, free, no signup.
Send HTTP requests from your browser — custom headers, bodies, params, saved collections, and one-click cURL/Fetch/Axios snippets. Developers debug a REST endpoint without leaving the tab — runs locally, free to start.
Build HTTP requests with method, URL, headers, and body — then generate matching curl commands. Prototype endpoints without leaving the tab — local, free, no signup.
Check if any number is prime. Also shows all factors and whether the number is odd or even. Numbers never leave your device — every calculation runs locally in your browser.
Computes exact age in years, months, and days from a given birth date relative to any target date. Numbers never leave your device — every calculation runs locally in your browser.
Non-simple methods, custom headers, or non-whitelisted content types.
Access-Control-Allow-Origin, Methods, Headers, and Credentials.
In your browser — the page itself issues the request, so verdicts reflect this origin. Results only, no account needed.
No account needed — inspections run without sign-in or saved history.