API Tester

Test REST APIs with custom headers, query parameters, and request body. Free online API testing tool.

What is API Tester?

API Tester is a free online tool that allows you to test REST APIs directly from your browser. Similar to Postman but without any installation required. You can send HTTP requests (GET, POST, PUT, DELETE, PATCH) to any API endpoint, customize headers, add query parameters, and view responses in real-time.

Perfect for developers who need to quickly test API endpoints, debug API issues, or verify API responses without switching applications. All processing happens in your browser - your API requests and responses never pass through our servers.

Key Features

  • ✓Support all HTTP methods: GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS
  • ✓Custom headers with easy enable/disable toggle
  • ✓Query parameters builder with URL preview
  • ✓Request body editor with support for JSON, Text, and Form Data
  • ✓Real-time response viewer with status code, headers, and formatted body
  • ✓Response time tracking for performance testing

How to Use API Tester

  1. Select the HTTP method (GET, POST, PUT, DELETE, etc.)
  2. Enter the API endpoint URL
  3. Add query parameters in the Params tab (optional)
  4. Add custom headers in the Headers tab (optional)
  5. For POST/PUT/PATCH requests, add request body in the Body tab

HTTP Methods Explained

GET

Retrieve data from the server. Used for fetching resources without modifying them.

POST

Send data to create a new resource on the server. Request body contains the data to be created.

PUT

Update an existing resource completely. Replaces the entire resource with new data.

DELETE

Remove a resource from the server. Typically no request body is needed.

PATCH

Partially update an existing resource. Only send the fields that need to be changed.

Common Use Cases

  • Testing REST API endpoints during development
  • Debugging API responses and error messages
  • Verifying authentication headers and tokens
  • Testing different HTTP methods on the same endpoint
  • Checking API performance and response times

Security & Privacy

Your privacy is our top priority. All API requests are sent directly from your browser to the target API server. We never intercept, store, or log your API requests, responses, headers, or any data you enter.

Note: This tool runs client-side in your browser, so it's subject to CORS (Cross-Origin Resource Sharing) restrictions. Some APIs may block requests from browsers. If you encounter CORS errors, you may need to test those APIs using server-side tools or enable CORS on the API server.

Frequently Asked Questions

Is this API tester completely free?

Yes! Our API Tester is 100% free with no limits on the number of requests. No registration or account required.

Do you store my API requests or responses?

No. All API requests are sent directly from your browser to the target server. We never see, store, or log any of your data. Everything happens client-side.

Why am I getting CORS errors?

CORS (Cross-Origin Resource Sharing) is a browser security feature. Some APIs don't allow requests from web browsers. To fix this, the API server needs to enable CORS headers, or you can use browser extensions that disable CORS, or use server-side testing tools.

Can I test APIs that require authentication?

Yes! You can add authentication headers (like Authorization: Bearer token) in the Headers tab. Common auth methods like API keys, Bearer tokens, and Basic Auth are all supported.

What's the difference between this and Postman?

Our API Tester runs entirely in your browser - no download or installation needed. It's perfect for quick testing. Postman is a desktop app with more advanced features like collections, environments, and automated testing. Use our tool for quick tests, use Postman for complex workflows.

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