CORS Headers Generator

Build Cross-Origin Resource Sharing headers interactively. Get config for HTTP, Express, Nginx, and Apache. 100% client-side.

Last reviewed: April 2026
Reviewed by , software engineer · last updated April 2026

New to this tool? Click here for instructions

Warning: Using * allows any domain. Cannot be combined with credentials.
Credentials mode requires specific origins, not wildcard (*).
Generated Config
Configure your CORS settings above. Output updates in real time.

How to Use the CORS Headers Generator

To use the CORS Headers Generator, follow these steps:

1. Set allowed origins - enter specific domain URLs or use * to allow all origins.

2. Select allowed methods - check the HTTP methods your API accepts (GET, POST, PUT, DELETE, PATCH, OPTIONS).

3. Configure headers - specify which request headers clients can send, and which response headers they can read.

4. Set max age - define how long browsers should cache preflight responses (in seconds).

5. Choose output format - select HTTP Headers, Express.js, Nginx, Apache, or .htaccess using the chips above.

6. Copy or download - use the buttons to copy the generated configuration to your clipboard or download it as a file.

When to Use the Tool in Real Workflows

Use the CORS Headers Generator when you need to configure CORS headers for your web server or API framework. This is particularly useful when you have frontend and backend deployed separately and need to allow cross-origin requests.

How It Works

The CORS Headers Generator creates the correct Access-Control-* HTTP headers for your web server or API framework. It allows you to configure allowed origins, methods, headers, and other settings interactively. The tool then generates the appropriate configuration for HTTP, Express.js, Nginx, Apache, or .htaccess based on your settings.

Tips, Edge Cases, or Limitations

1. Be cautious when using * in Access-Control-Allow-Origin as it allows any domain and cannot be combined with credentials.

2. Ensure that the Access-Control-Allow-Origin header does not conflict with the Access-Control-Allow-Credentials header.

3. Understand that preflight requests are necessary for non-simple requests and can be cached for a specified duration using Access-Control-Max-Age.

4. Always test your CORS configuration thoroughly to ensure it works as expected in your production environment.

Frequently Asked Questions

CORS (Cross-Origin Resource Sharing) is a browser security mechanism that restricts web pages from making requests to domains different from the one that served the page.
No, your configuration data is not sent to a server. All processing occurs in your browser.
Using * allows any domain and cannot be combined with credentials. It is generally not recommended for production environments due to security concerns.
A preflight request is an OPTIONS request sent by the browser to the server to determine if the actual request is permitted. It is necessary for non-simple requests.
Common issues include incorrect configuration of Access-Control-Allow-Origin, Access-Control-Allow-Methods, or Access-Control-Allow-Headers. Always test your configuration thoroughly to ensure it works as expected in your production environment.

Quick reference

CORS Headers Generator Quick Reference
Header Name Description Common Values Example
Access-Control-Allow-Origin Specifies the origins allowed to access the resource * (all origins), https://example.com https://example.com
Access-Control-Allow-Methods Lists the HTTP methods permitted GET, POST, PUT, DELETE GET, POST, PUT
Access-Control-Allow-Headers Defines the headers allowed in requests Content-Type, Authorization Content-Type, Authorization
Access-Control-Allow-Credentials Indicates if credentials are allowed true, false true
Access-Control-Expose-Headers Specifies headers available to the client X-Custom-Header X-Custom-Header
Access-Control-Max-Age Defines how long the response is cached 86400 (seconds) 86400