API Tester Online
Send HTTP requests to any API endpoint directly from your browser. Add custom headers, set request bodies, and inspect responses — a lightweight Postman alternative that runs entirely client-side.
How the API Tester Online Works
This free browser-based API tester lets you send HTTP requests to any publicly accessible endpoint without installing software or creating an account. It uses the browser's native fetch() API to make real HTTP calls and displays the full response including status code, headers, and body.
How Requests Are Sent
When you click Send Request, the tool constructs a fetch() call with your chosen HTTP method, URL, headers, and body. The response is captured along with timing data, then parsed and displayed. JSON responses are automatically formatted for readability.
Supported HTTP Methods
The tool supports all standard HTTP methods: GET for retrieving data, POST for creating resources, PUT and PATCH for updating resources, DELETE for removing resources, HEAD for retrieving headers without a body, and OPTIONS for checking CORS preflight information.
Working with Request Bodies
For POST, PUT, and PATCH methods, you can attach a request body in three formats. JSON mode automatically sets the Content-Type header to application/json. Form Data mode uses application/x-www-form-urlencoded encoding. Raw mode sends the body as plain text with no automatic content type.
Understanding CORS Limitations
Because this tool runs in a browser, requests are subject to Cross-Origin Resource Sharing (CORS) policies. If the target API does not include CORS headers in its response, the browser will block the response from being read. This is a browser security feature, not a bug. APIs designed for browser access typically include CORS headers. For APIs that do not support CORS, you may need to use a server-side proxy or a dedicated API client like Postman or curl.
Privacy and Security
All requests are sent directly from your browser to the target API. No data passes through our servers. Your URLs, headers, authentication tokens, and request bodies remain completely private. This makes the tool safe for testing endpoints that require sensitive credentials.
When to Use This Tool
Use this API tester for quick endpoint verification during development, debugging webhook responses, testing REST APIs before integrating them into your application, or learning how HTTP methods work. It is ideal for situations where installing a full-featured API client is unnecessary or impractical.