API Tester

What is API Tester?

An API tester (also called an HTTP client or REST client) is a tool that allows you to send HTTP requests to web APIs and inspect the responses. Unlike browser-based requests that are limited to GET, API testers let you use any HTTP method, set custom headers, include request bodies, and see detailed response information including status codes, headers, and body content.

Common Use Cases

• API development - test endpoints during development and debugging
• Integration testing - verify API integrations work correctly
• API documentation - test and understand API behavior
• Debugging - troubleshoot API issues by inspecting requests and responses
• Learning - understand how different HTTP methods and headers work
• Quick testing - rapidly test APIs without installing desktop applications
• API exploration - discover and test public APIs

How It Works

The API tester sends HTTP requests using the browser's Fetch API. You specify the URL, HTTP method (GET, POST, etc.), add custom headers (like Authorization tokens), set query parameters, and include request bodies (JSON, form data, etc.). The tool sends the request and displays the response including status code, response headers, and body content. All requests are made from your browser, so they're subject to CORS policies.

Examples

Method: GET, URL: https://api.example.com/users?page=1&limit=10

Status: 200 OK, Response: JSON array of users

Method: POST, URL: https://api.example.com/users, Body: {"name":"John"}

Status: 201 Created, Response: Created user object