What does this tool do?
The CORS header generator produces the Access-Control-* HTTP headers needed to allow cross-origin requests from browsers. It is ideal for developers building APIs, debugging CORS errors between a frontend and backend, or quickly drafting server configuration.
How to use it
- Choose the required options or length.
- Generate the secure result.
- Copy and store the result safely.
Which headers it generates
From your allowed origin, methods, allowed headers, credentials, and Max-Age, the tool builds Access-Control-Allow-Origin, Access-Control-Allow-Methods, Access-Control-Allow-Headers, Access-Control-Allow-Credentials, and Access-Control-Max-Age. You can toggle methods (GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS) with one click and export the result as plain HTTP, an Nginx add_header block, or Express middleware.
Origin and credentials caveat
The origin field accepts a single source (https://example.com) or * for any origin. However, when Access-Control-Allow-Credentials is true, browsers reject a wildcard * origin, so you must specify one exact origin. Max-Age sets how many seconds the browser caches the preflight (OPTIONS) response; 86400 (24 hours) is a common value that reduces repeated preflight requests and improves performance.
Frequently asked questions
How do I export as Nginx, Express, or raw headers?
Use the raw, nginx, and express tabs above the output box. raw gives plain HTTP headers, nginx gives add_header directives, and express gives a middleware block with res.header calls.
Why can't I allow credentials when origin is *?
The CORS spec forbids a wildcard * Allow-Origin when credentials is true. If you send cookies or an Authorization header, specify an exact origin such as https://app.example.com.
What does Access-Control-Max-Age do?
It sets how many seconds the browser caches the preflight OPTIONS response. A higher value avoids re-sending preflight requests for the same call, improving performance.
Is CORS Header Generator free?
Yes. CORS Header Generator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. CORS Header Generator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.