CORS Header Generator

Create and configure CORS headers for cross-origin requests.

Use '*' to allow all origins (cannot be used with credentials)
0 (no cache)86400 (24 hours)

Generated CORS Headers

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization
Access-Control-Max-Age: 3600

When to use this generator

  • A browser calls your API from another origin (different scheme, host, or port) and the console shows a CORS or preflight failure.
  • You are writing infra-as-code, nginx, API Gateway, or Lambda config and need the exact header lines to paste.
  • You want to compare a strict setup (named origins, no credentials) vs a dev-only relaxed setup before you lock production.

Real-world example

A React app at https://app.example.com posts JSON with Authorization to https://api.example.com. You allow that origin (not *), include OPTIONS, list Content-Type and Authorization in allow-headers, and set Allow-Credentials: true because you use cookies—this tool outputs the matching header block for you to wire into the server.

Common mistakes

  • * with credentials: browsers reject it; list explicit origins.
  • Missing custom headers (e.g. X-Request-Id) in allow-headers—preflight fails even when GET works.
  • Forgetting OPTIONS on the server route so preflight never returns 204/200 with these headers.

Limitations of this tool

  • It only builds static header text—your framework may need middleware syntax (Express cors(), Spring config, etc.).
  • It does not model dynamic origin allowlists, regex origins, or per-route policies—you must merge that logic yourself.
  • CORS is not a substitute for authn/authz; permissive headers do not make an API safe.
By Muhammad Abdullah Rauf · Founder, EverydayTools.proUpdated 2026-05-28· Reviewed by EverydayTools Editorial Team

What is CORS Header Generator?

Create and configure CORS headers for cross-origin requests. Use it in your browser without uploading files for typical workflows.

Free CORS header generator — configure Access-Control-Allow-Origin, methods, headers, and credentials. Preview the full CORS response header block instantly. No signup. Runs locally in your browser when supported—no upload required for normal use. Designed for quick everyday tasks with clear, copy-friendly output.

Quick answers

Concise answers for common searches — definitions, steps, and comparisons.

What does CORS Header Generator do?

Create and configure CORS headers for cross-origin requests.

Is CORS Header Generator private?

CORS Header Generator (/cors-header-generator) runs in your browser when supported—inputs are not uploaded to EverydayTools servers.

How to use CORS Header Generator

  1. Open the tool

    Load CORS Header Generator on EverydayTools—no account required.

  2. Enter your input

    Type, paste, or upload depending on what the tool accepts.

  3. Review results

    Results update in your browser for typical use cases.

  4. Copy or export

    Copy the output or use download/export when available.

Who uses CORS Header Generator?

Common real-world scenarios where this tool saves time.

Everyday use

Create and configure CORS headers for cross-origin requests.

Privacy-first workflows

Use when you want results without uploading files—local browser processing when the tool supports it.

Mobile and desktop

Open CORS Header Generator in any modern browser for quick checks with copy-friendly output.

Workflow guides

Step-by-step chains that connect related tools for common tasks.

Configure CORS for a REST API endpoint

  1. Enter your allowed origin (e.g. https://app.example.com), methods (GET, POST, PUT), and custom headers (Authorization, Content-Type).
  2. Copy the generated header block into your server config (NGINX location block, Express middleware, or API Gateway response header mapping).
  3. Convert any curl test command to a fetch() call with cURL to Fetch Converter to verify the request includes the correct headers.

Reference tables

CORS Header Generator at a glance

How this EverydayTools page compares for typical use.

AspectEverydayToolsTypical alternative
CostFreePaid apps or trials
PrivacyBrowser-local when supportedOften requires cloud upload
SignupNot requiredOften required

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Frequently Asked Questions

What does Access-Control-Allow-Origin do?

Access-Control-Allow-Origin tells the browser which origins are permitted to read the response. Setting it to * allows any origin; setting it to https://example.com restricts access to that specific domain. Without this header, browsers block cross-origin fetch and XHR responses under the Same-Origin Policy.

Why do I need Access-Control-Allow-Credentials?

When your request includes cookies or HTTP authentication, set Access-Control-Allow-Credentials: true on the server. The browser will only expose the response to JavaScript if this header is present. Note: you cannot combine credentials:true with Access-Control-Allow-Origin: * — you must specify the exact origin.

What is a CORS preflight request?

Browsers send an OPTIONS preflight before 'non-simple' cross-origin requests (custom headers, non-GET/POST methods, or JSON content-type). The server must respond with the appropriate Access-Control headers. This tool generates the full preflight response header block so you can configure your server or API gateway correctly.

Which HTTP methods require CORS configuration?

All cross-origin requests need CORS headers, but simple requests (GET, POST with basic content types) bypass preflight. Methods like PUT, PATCH, DELETE, or any request with custom headers (Authorization, Content-Type: application/json) always trigger a preflight. Include all used methods in Access-Control-Allow-Methods.

What does CORS Header Generator do?

Create and configure CORS headers for cross-origin requests.

Privacy, accuracy, and trust

Privacy

CORS Header Generator keeps typical inputs on your device—nothing is uploaded to EverydayTools servers for core calculations.

Related Tools

More free tools for the same workflow.

cURL to Fetch Converter

Free cURL to fetch converter — paste any cURL command and instantly get the equivalent JavaScript fetch() code with all headers, methods, and body included. No signup needed. Runs locally in your browser when supported—no upload required for normal use.

HTTP Header Generator

Free HTTP header generator — build Content-Type, Cache-Control, CORS, Authorization, and security headers with correct syntax. Copy for NGINX, Apache, or API responses. No signup. Runs locally in your browser when supported—no upload required for normal use.

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Reviewed by EverydayTools Editorial Team on 2026-05-28.