CORS Config Generator

Create ready-to-use CORS policies for Laravel, Express, Nginx, Apache, S3, and Cloudflare.

CORS Config Generator

Generate ready-to-use CORS policies for popular frameworks and servers.

Settings

Use full origins like https://example.com. Wildcards like https://*.example.com work for Nginx/Apache patterns.
Example: Content-Type, Authorization, X-Requested-With
Only needed if the browser must read custom response headers.
How long the browser can cache the preflight response.
If enabled, do not use * for Access-Control-Allow-Origin.

Generated configuration

Your output will appear here. Choose a target platform, add the origins you want to allow, then click Generate. You can copy or download the final configuration snippet.

About CORS Config Generator

CORS Config Generator – Create Secure Cross‑Origin Policies

Cross-Origin Resource Sharing (CORS) is one of those settings you only notice when something breaks: a frontend can’t call an API, a browser blocks a request, or cookies stop flowing in production. This CORS Config Generator helps you build correct, copy‑pasteable configurations for popular stacks without guessing headers or missing preflight details.

Whether you’re shipping a Laravel API, an Express backend, a static site backed by S3, or a reverse proxy on Nginx, the tool produces a clear configuration snippet and a readable summary so you can validate the policy before deploying.

How It Works

The generator takes a short set of inputs—origins, methods, headers, and a few behavioral options—and then converts them into the exact syntax required by each target environment. Because different platforms express CORS in different ways (arrays in PHP, middleware options in JavaScript, directives in Nginx/Apache, or XML in S3), the tool focuses on producing output that is both valid and practical.

What you provide

  • Allowed origins: one origin per line (for example https://example.com or http://localhost:3000).
  • Methods: check the HTTP methods your API or server should accept cross‑origin.
  • Allowed headers: request headers your client will send (such as Authorization or Content-Type).
  • Exposed headers: response headers that JavaScript should be able to read.
  • Max‑Age: how long a browser can cache the preflight response.
  • Credentials: enable this only if you need cookies or authenticated requests across origins.

After you click Generate, the result panel shows a ready-to-use snippet and a compact summary of the policy choices. You can copy the snippet or download it as a file with an extension that matches the target platform.

Key Features

Multi-platform output

Generate configuration for Laravel, Express, Nginx, Apache, AWS S3, and Cloudflare Workers. Each output is formatted in the style developers expect in that environment.

Preflight-aware generation

CORS issues often come from missing OPTIONS handling. The generator includes sensible preflight handling patterns for Nginx and Apache, and shows the right middleware call for Express.

Safe, explicit inputs

The tool encourages you to list concrete origins. This reduces accidental overexposure that can happen when copying a permissive “allow all” snippet into production.

Readable summaries

Alongside the snippet, you get a human-friendly summary of origins, methods, and headers. This makes it easier to review your policy during code review or incident response.

Copy and download workflow

One click copies the final snippet to your clipboard, and another click downloads it as a small text file you can drop into a repo or attach to a ticket.

Use Cases

  • Frontend + API development: connect a React/Vue/Angular app to a local or remote API without fighting the browser.
  • Microservices and gateways: generate proxy-level CORS rules for Nginx when multiple services sit behind one domain.
  • Authentication and sessions: configure credentialed requests for cookie-based auth or token-based APIs.
  • Static assets with APIs: allow a site hosted on one domain to call APIs on another, including S3-backed assets.
  • Edge deployments: set correct CORS headers in Cloudflare Workers so edge logic doesn’t break browsers.
  • Quick audits: produce a clear, reviewable policy summary when security teams ask what is allowed.

CORS is both a security control and an availability requirement. The best policies are narrow enough to reduce risk, but flexible enough to support legitimate applications. This generator is designed to help you strike that balance quickly.

Optimization Tips

Prefer specific origins over wildcard

Using * is easy, but it is rarely the right production choice—especially if you enable credentials. Browsers disallow credentialed requests with Access-Control-Allow-Origin: *, and a wildcard can unintentionally grant access to unexpected websites.

Keep allowed headers minimal

Many APIs only need a few headers (often Content-Type and Authorization). If you allow too many headers, you make it easier for third-party scripts to send extra metadata across origins. Only add headers that your client truly requires.

Use Max-Age to reduce preflight load

Preflight requests can be chatty. Setting a reasonable Max-Age (for example 3600–86400 seconds) can reduce load and improve perceived latency. When debugging, you can temporarily lower it so changes propagate faster.

FAQ

CORS is a browser security model that limits which websites can make cross-origin requests to another domain. If your server doesn’t send the right CORS headers, the browser blocks the response even if the network request succeeded.

Enable credentials when your browser requests must include cookies, HTTP authentication, or other credentialed signals. If you turn it on, you must also avoid wildcard origins and explicitly list allowed origins.

That’s a preflight request. Browsers send OPTIONS to check whether the server allows a cross-origin request with your method and headers. If preflight fails, the browser won’t proceed with the actual request.

Some platforms support pattern matching and some don’t. The generator treats wildcards as patterns for server configs like Nginx/Apache. For application-level middleware (Laravel/Express), it’s usually better to list exact origins or implement custom logic.

Allowed headers are request headers the browser is permitted to send. Exposed headers are response headers JavaScript is allowed to read. If a response header isn’t exposed, it may still be present on the network level, but your frontend code can’t access it.

Why Choose This Tool

CORS is deceptively simple: add a couple of headers and you’re done. In practice, small mismatches between environments—like forgetting to handle OPTIONS, enabling credentials with wildcard origins, or omitting required request headers—can cause hours of debugging and fragile “temporary fixes.” This generator gives you a consistent, reviewable starting point tailored to the platform you actually deploy.

Because the output is explicit, it also helps you think about security: which sites can call your API, which methods are truly needed, and which headers you should permit. Use it to move faster during development and reduce surprises in production—while keeping cross-origin access tight and intentional.

Understanding the Inputs

If you’ve ever copied a CORS snippet from a blog post, you’ve probably seen different combinations of headers and options. The differences usually come from the exact request your browser is sending. “Simple” requests (like a plain GET without custom headers) may not need preflight, while requests that include JSON bodies, authorization tokens, or nonstandard headers almost always trigger OPTIONS first.

This is why the generator lets you control methods and headers explicitly. A mismatch is common: for example, your frontend sends Authorization, but the server only allows Content-Type, so the browser rejects the preflight response. By listing the headers you actually send, you align server behavior with browser expectations.

Origins: the most important decision

An origin is the combination of scheme, host, and port. https://example.com and https://example.com:8443 are different origins. During development you may also have http://localhost:5173, http://localhost:3000, and a staging domain. It’s normal to allow multiple origins, but you should still keep the list as small as possible.

Credentials: powerful but easy to misuse

Credentialed requests are required for cookie-based sessions and for some authentication flows. When enabled, the browser requires an explicit allow-origin response that matches the requesting origin. In other words, * is not allowed with credentials. If you enable this option, consider using a dedicated frontend domain, keep origin lists specific, and verify that your API responses never reflect untrusted origins.

Common Deployment Patterns

API on a subdomain

A frequent setup is https://app.example.com for the frontend and https://api.example.com for the backend. In this case, you typically allow the frontend origin on the API and keep the policy narrow. If you use cookies, enable credentials and ensure your cookie attributes (SameSite, Secure, Domain) are consistent with the browser’s rules.

Reverse proxy in front of multiple services

If Nginx sits in front of several upstream services, handling CORS at the proxy layer can simplify applications. The proxy can respond to OPTIONS requests consistently while forwarding non-preflight traffic to upstreams. The generator’s Nginx output is meant as a readable baseline; you can adapt it to your location blocks and security standards.

Static hosting and edge compute

When static files are hosted in S3 and business logic runs at the edge (for example Cloudflare Workers), CORS needs to be correct on the responses that reach the browser. S3’s XML format differs from header-based systems, and some options like credentials may require additional application logic. The generator includes notes where platform capabilities differ so you can avoid surprises.

Debugging checklist

If something still fails, inspect the browser’s network panel. Confirm the request origin, look at the preflight response headers, and compare them to what your frontend sends. Most issues come down to one of three things: missing OPTIONS handling, missing allowed headers, or a mismatch between credential mode and allow-origin behavior.