API Tester
Test REST APIs directly from your browser. Send HTTP requests, inspect responses, and debug endpoints — no installation needed.
Send a request to see the response
Supports GET, POST, PUT, PATCH, DELETE and more
Free Online API Tester — Test REST APIs in Your Browser
Building and debugging APIs is one of the most common tasks in web development. Whether you are working on a REST API, testing a third-party integration, or verifying that your backend returns the right data, you need a tool that lets you send HTTP requests quickly and see exactly what comes back.
The OmniWebKit API Tester is a free, browser-based HTTP client that lets you do exactly that. You do not need to install Postman, configure an IDE plugin, or write a single line of code. Just enter a URL, choose your HTTP method, add headers or a request body if needed, and hit Send. The response appears instantly — status code, response time, response size, body, and all response headers included.
This tool is perfect for frontend developers testing backend APIs, QA engineers verifying endpoint behaviour, students learning how HTTP works, and anyone who needs to make a quick API call without pulling up a full desktop application.
How to Use the API Tester
Enter Your API URL
Type or paste the full API endpoint URL into the address bar at the top. For example: https://api.example.com/users. You can also click any Quick Preset to load a real-world API URL instantly.
Choose an HTTP Method
Select the method from the dropdown: GET to retrieve data, POST to create, PUT to replace, PATCH to partially update, or DELETE to remove a resource. HEAD and OPTIONS are also supported for advanced use cases.
Add Headers and Parameters
Use the Headers tab to add authentication tokens (Authorization: Bearer …), content type declarations, or any custom headers. Use the Params tab to add query parameters like ?page=1&limit=10 — they are appended to the URL automatically.
Add a Request Body
For POST, PUT, and PATCH requests, switch to the Body tab and enter your JSON payload. Use the Beautify JSON button to auto-format messy JSON before sending. The editor uses a dark terminal-style background for comfortable reading.
Send and Inspect the Response
Click Send (or press Enter) to fire the request. The response panel shows the HTTP status code (200, 404, 500 etc.), response time in milliseconds, body size, and the full response body with JSON syntax highlighting. Switch to the Headers tab in the response panel to see all response headers.
Use Request History
Every successful request is saved in your session history. Click any history item to restore that URL and method so you can re-run or modify it. You can clear the history at any time.
Key Features
All HTTP Methods
Supports GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS requests.
JSON Syntax Highlighting
Response JSON is colour-highlighted for keys, strings, numbers, booleans, and null values.
Query Parameter Builder
Add query parameters visually. They are encoded and appended to the URL automatically.
Custom Request Headers
Add any headers including Authorization, Accept, X-API-Key, and Content-Type with simple key-value pairs.
Request History
Automatically saves your last 20 requests. Click any history item to reload that request instantly.
Quick Presets
Load real-world API examples in one click — JSONPlaceholder, GitHub, IP geolocation, and more.
Response Metadata
See the exact HTTP status code, status text, response time (ms), and response body size for every request.
One-click Copy
Copy the full response body or individual response header values to clipboard with a single click.
HTTP Methods Explained
REST APIs use different HTTP methods to represent different actions on a resource. Choosing the right method is fundamental to building and testing APIs correctly. Here is what each method means and when to use it.
Retrieve a resource or list of resources. GET requests should never modify data. They are safe and can be cached.
Create a new resource. Send data in the request body. The server returns the created resource, usually with a 201 Created status.
Replace an entire resource with the data in the request body. If the resource does not exist, some APIs will create it.
Partially update a resource. Only send the fields you want to change. More efficient than PUT when updating one or two fields.
Remove a resource permanently. A successful delete typically returns 200 OK or 204 No Content with an empty body.
Like GET, but returns only the response headers — not the body. Useful for checking if a resource exists or checking cache metadata.
Returns the HTTP methods the server supports for a URL. Used by browsers in CORS preflight requests before cross-origin API calls.
HTTP Status Codes You'll See
Every HTTP response includes a three-digit status code. Understanding what these codes mean is essential for debugging APIs. The API Tester colour-codes them for quick identification — green for success, blue for redirects, amber for client errors, and red for server errors.
200 OK, 201 Created, 204 No Content
The request was received, understood, and processed successfully. 200 is the standard success code. 201 means a resource was created. 204 means success but no content to return.
301 Moved Permanently, 302 Found, 304 Not Modified
The client must take additional action to complete the request. 301 means the URL has permanently changed. 304 means the cached version is still valid.
400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found
The request contained an error on the client side. 400 means bad syntax. 401 means authentication is required. 403 means you are authenticated but not allowed. 404 means the resource was not found.
500 Internal Server Error, 502 Bad Gateway, 503 Service Unavailable
The server failed to fulfil a valid request. 500 is a generic server-side error. 502 means the gateway received an invalid response. 503 means the server is temporarily unavailable.