API Request Builder - Online Test REST Endpoints

REST (Representational State Transfer) APIs allow applications to communicate over HTTP using standard methods like GET, POST, PUT, and DELETE. This API Request Builder lets you construct and send HTTP requests directly from your browser to any REST endpoint. You can customize headers, query parameters, and request bodies, then inspect the full response — including status codes, response headers, and body content — making it an essential tool for API development, debugging, and integration testing without needing to install separate software.

CORS (Cross-Origin Resource Sharing) is a browser security mechanism that restricts web pages from making requests to a different domain than the one serving the page. If the target API server doesn't include appropriate Access-Control-Allow-Origin headers in its response, the browser will block the request for security reasons. This is not a bug in the tool — it's a fundamental browser security policy. To work around this, you can test with public APIs that support CORS (like JSONPlaceholder, GitHub API, or httpbin), use a browser extension that temporarily disables CORS (for development only), or set up a local CORS proxy server. Many production APIs do support CORS for web application integration.

This tool supports all standard HTTP methods: GET (retrieve data without side effects), POST (create new resources), PUT (replace or create a resource at a specific URI), PATCH (partially update an existing resource), DELETE (remove a resource), HEAD (retrieve headers only, identical to GET without the response body), and OPTIONS (discover supported methods and CORS policies for an endpoint). Choose the method that matches the operation you intend to perform — most read-only operations use GET, while data modifications typically use POST, PUT, or PATCH.

To send JSON data: (1) Set the HTTP method to POST, PUT, or PATCH. (2) In the Body tab, select application/json as the Content-Type. (3) Enter your valid JSON in the text editor — the tool will validate your JSON syntax automatically. (4) Ensure the Headers tab includes Content-Type: application/json (this is set automatically when you choose the JSON content type). (5) Click Send. The request body will be transmitted as a JSON string, and most modern APIs will parse it correctly on the server side.

Yes! This tool automatically saves your request history in your browser's local storage. Click the clock icon next to the Send button to open the history panel. Each entry shows the HTTP method, URL, and timestamp. Click any history item to instantly restore that request — including the method, URL, headers, and body — so you can quickly re-send or modify previous requests. Your history persists across browser sessions until you clear it. Use the Clear All button to remove all stored history entries.

HTTP status codes are grouped into five categories: 2xx (Success) — the request was processed successfully (e.g., 200 OK, 201 Created); 3xx (Redirection) — further action is needed (e.g., 301 Moved Permanently, 304 Not Modified); 4xx (Client Error) — the request contains an error on your side (e.g., 400 Bad Request, 401 Unauthorized, 404 Not Found); 5xx (Server Error) — the server failed to process a valid request (e.g., 500 Internal Server Error, 503 Service Unavailable). This tool color-codes the status badge for quick visual identification: green for success, blue for redirection, orange for client errors, and red for server errors.