API Tester - Test REST API Online

Test API endpoints directly from the browser

Request

Response

Send a request to see the response

⚠️ Notes on CORS:

Some APIs may be blocked by the browser's CORS policy. To test these APIs, you need to use Postman or cURL.

API Tester Online - Professional free REST API Testing tool

Tan Phat Digital's API Tester tool is the perfect solution for developers who need to quickly test REST API endpoints directly from the browser without installing software. Fully supports HTTP methods: GET, POST, PUT, PATCH, DELETE with flexible customization capabilities. Customize headers with an intuitive key-value interface, JSON body editor with syntax highlighting for POST/PUT/PATCH requests, display response body with beautiful JSON formatting, view detailed response headers with all metadata, and measure response times down to milliseconds to evaluate performance. Intuitive Postman-like interface with color-coded status codes helps quickly identify success (2xx in blue), redirect (3xx in yellow), client error (4xx in orange), and server error (5xx in red). The tool is completely free, no need to register an account, handles directly from your browser with CORS issues warnings and detailed resolution instructions. Especially useful for frontend developers who need to test backend APIs, backend developers who need to verify endpoints after deployment, QA engineers who need manual testing, and students learning about REST API concepts.

Outstanding features

Full support for HTTP methods: GET, POST, PUT, PATCH, DELETE
Custom headers with an easy-to-use key-value interface
JSON body editor cho POST, PUT, PATCH requests
Display response body with JSON formatting
See details of response headers
Color-coded status codes: 2xx green, 4xx orange, 5xx red
Measure the exact response time (milliseconds)
Copy response with one click
Preset Content-Type header default
Warning CORS issues with resolution instructions

Why do developers need API Tester tools?

During API development and debugging, developers need to test endpoints regularly to verify functionality, check response format, and debug issues. Postman is a popular tool but requires installation and can be heavy for quick tests. API Tester online allows testing right on the browser, no installation required, convenient when working on another computer or needing to share tests with the team. The tool is especially useful for quick debugging, verifying APIs after deployment, demoing APIs for stakeholders, and learning about REST APIs for beginners.

Benefits when used

  • •Test API right in the browser, no need to install software
  • •Convenient for quick debugging and verification
  • •Simple interface, easier to use than Postman for basic tests
  • •See response time to evaluate performance
  • •Color-coded status helps quickly identify
  • •results Learning REST API concepts for beginners
  • •Share test results easily via screenshot
  • •Completely free, unlimited requests

Detailed instructions on how to test API online

  1. 1Select HTTP method from the dropdown: GET, POST, PUT, PATCH, or DELETE
  2. 2Enter the full endpoint URL (including https://)
  3. 3Add headers if needed: Authorization, API keys, custom headers
  4. 4With POST/PUT/PATCH, enter JSON body in textarea
  5. 5Click
  6. 6to send request
  7. 7View status code and response time
  8. 8Check response headers and body
  9. 9Copy response if needed using

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