Are UtiliTools really 100% free?

Yes, all 115+ tools on UtiliTools are completely free with no hidden costs, no premium plans, and no usage limits. The site is supported by non-intrusive advertising.

Do I need to create an account or sign up?

No, UtiliTools requires no sign-up, no email, and no account. Just open any tool and start using it immediately.

Are my files safe? Do you upload them to a server?

Your files are 100% safe. Almost all UtiliTools process files directly in your browser using JavaScript and WebAssembly. Your files never leave your device and are never uploaded to any server.

What tools are available on UtiliTools?

UtiliTools offers 115+ tools across 6 categories: PDF tools (convert, compress), Image tools (convert, compress, resize), Video tools (convert, extract audio), Text tools (case converter, diff, markdown), Developer tools (JSON formatter, Base64, hash generator, regex tester, and more), and Utilities (QR codes, unit converter, password generator, timer).

Does UtiliTools work on mobile devices?

Yes, UtiliTools is fully responsive and works on smartphones, tablets, and desktops. All tools are optimized for touch interfaces and smaller screens.

How is UtiliTools different from other online tool websites?

Unlike most online tool websites, UtiliTools processes your files directly in your browser — no uploads, no server processing, no waiting. This means faster results and complete privacy. Plus, there are no file size limits or daily usage caps.

CORS (Cross-Origin Resource Sharing) is a security mechanism that allows or restricts web pages from making requests to a different domain than the one that served the page. It uses HTTP headers to control access.

What is a CORS preflight request?

A preflight request is an OPTIONS request sent by the browser before certain cross-origin requests to check if the actual request is safe to send. It verifies allowed methods, headers, and origin.

Why do CORS errors occur?

CORS errors occur when a server does not include the appropriate Access-Control-Allow-* headers in its response, preventing the browser from allowing the cross-origin request.

home/cybersecurity/cors-tester

CORS Tester

Test Cross-Origin Resource Sharing (CORS) headers of any URL directly from your browser. Check allowed origins, methods, headers and credentials support with preflight analysis.

URL to test

Origin (default: current page)

Method:

Custom Headers

Enter a URL above to test its CORS configuration.

Preflight requests

Browsers send an OPTIONS preflight request before certain cross-origin requests to verify the server allows the actual request method and headers.

Allow-Origin

The Access-Control-Allow-Origin header is the most critical CORS header. It specifies which origins can access the resource. A wildcard (*) allows all origins.

Credentials

When Access-Control-Allow-Credentials is true, the browser allows cookies and auth headers. This cannot be used with a wildcard origin.

How to Use CORS Testing Tool

The CORS Testing Tool lets you simulate cross-origin requests to verify how a server handles Cross-Origin Resource Sharing policies. Test preflight OPTIONS requests, check allowed origins, methods, and headers, and diagnose CORS errors that block your frontend from accessing APIs. Essential for web developers working with APIs.

Open the CORS Tester

Navigate to the CORS Testing Tool from the cybersecurity tools menu. The interface provides fields for configuring a cross-origin request simulation.

Enter the Target URL

Type or paste the API endpoint URL you want to test. This is the URL your frontend application is trying to access that may be returning CORS errors.

Configure Request Parameters

Set the origin domain, HTTP method (GET, POST, PUT, DELETE), and any custom headers your application sends to fully simulate the cross-origin request.

Execute the CORS Test

Click the test button to send a preflight OPTIONS request and the actual request to the server, capturing all CORS-related response headers.

Analyze the Results

Review the Access-Control-Allow-Origin, Access-Control-Allow-Methods, Access-Control-Allow-Headers, and Access-Control-Allow-Credentials headers in the response.

Common Use Cases

Debugging Frontend API Calls

Identify exactly which CORS header is missing or misconfigured when your JavaScript application fails to fetch data from a cross-origin API.

Verifying Server Configuration

Test that your backend API server returns correct CORS headers for all expected origins, methods, and headers before deploying to production.

Security Assessment of CORS Policies

Evaluate whether an API's CORS configuration is too permissive (allowing any origin) or properly restricted to known trusted domains.

Microservice Integration Testing

Verify CORS settings across multiple microservices that need to communicate with different frontend applications hosted on various domains.

Pro Tips

-Remember that CORS is enforced by browsers, not servers. A CORS error means the server response lacks the correct headers, not that the request failed on the server.
-The wildcard origin (*) cannot be used together with credentials (cookies). If you need credentials, specify exact allowed origins on the server.
-Preflight requests only occur for non-simple requests. Simple GET and POST requests with standard headers may skip the OPTIONS check entirely.
-If your API returns CORS headers on GET but not on OPTIONS, the preflight will fail even though the actual request would succeed.

📋