What is the purpose of the `Access-Control-Max-Age` header?

It instructs the browser how many seconds to cache the results of a preflight OPTIONS request, reducing redundant network requests.

Web Developer Tools

CORS Header Generator

Generate Cross-Origin Resource Sharing (CORS) header directives for web servers.

CORS Configuration

Access-Control-Allow-Origin:Access-Control-Allow-Methods:Access-Control-Allow-Headers:

Results & Code Snippets

# Express / Node.js CORS Middleware
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
  res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization');
  next();
});

About CORS Header Generator

The Cross-Origin Resource Sharing (CORS) Header Generator configures HTTP headers (`Access-Control-Allow-Origin`, `Access-Control-Allow-Methods`, `Access-Control-Allow-Headers`, `Access-Control-Allow-Credentials`) for NGINX, Apache, Express.js, Next.js, and AWS API Gateway.

Step-by-Step Guide

How to Use CORS Header Generator

Step 1

Enter your allowed frontend origins (e.g. `https://example.com`).

Step 2

Select allowed HTTP methods and request headers.

Step 3

Choose your server environment (NGINX, Express, Apache, Next.js).

Step 4

Copy the generated server configuration snippet.

Industry Scenarios

Practical Use Cases for CORS Header Generator

Resolving Browser CORS Block Errors

Eliminate `No 'Access-Control-Allow-Origin' header is present on the requested resource` browser console errors in REST and GraphQL APIs.

Secure Cross-Origin Authentication

Configure `Access-Control-Allow-Credentials: true` with strict explicit origins for cookie-based session authentication.

Sample Data & Transformation

Input & Output Examples

Generating CORS Configuration for Express.js

Input Sample:

Origin: https://app.renderxd.com, Methods: GET,POST,PUT,DELETE, Credentials: True

Processed Result:

Express CORS middleware & raw HTTP headers configured with strict origin matching

Technical Capabilities

Key Features & Performance

✓Generates copy-paste configurations for NGINX, Apache (.htaccess), Express.js (Node.js), Next.js route handlers, and Fastify.
✓Configures Allowed Origins, HTTP Methods, Allowed Headers, Exposed Headers, and Max-Age preflight cache.
✓Warns against insecure wildcard (`*`) origin with credentials combinations.
✓100% Client-Side generation.
✓1-Click Copy code.

Technical Glossary

Key Terminology & Definitions

CORS Preflight Request (OPTIONS)

An automatic HTTP OPTIONS request sent by browsers before the actual request to verify that the server allows the cross-origin operation.

Access-Control-Allow-Origin

An HTTP response header indicating whether the response can be shared with requesting code from the given origin.

Frequently Asked Questions (PAA)

CORS Header Generator FAQs

Web security standards strictly prohibit wildcard (`*`) origins when `Access-Control-Allow-Credentials: true` is enabled to protect cookies and authorization headers.