API Testing Tool
Free in-browser API testing tool (Postman alternative). Fire HTTP requests (GET, POST, PUT, DELETE, etc.) against any URL straight from your browser with custom headers and body.
Fire HTTP requests at any endpoint straight from the browser — no install, no account, no workspace to set up. Choose the method, enter a URL, add headers and a body, and send. It's the quick API check you reach for when opening Postman feels like overkill, and the API endpoint also returns the equivalent cURL command for scripts and CI.
The method behind the numbers
The sandbox issues the request from your browser using the Fetch API and shows you the response status, headers and body. Because it runs client-side, it's bound by the same cross-origin (CORS) rules as any web page: an API that doesn't send permissive CORS headers will block a browser-origin request, even though the same call works from a terminal.
The companion API endpoint validates and normalises your request and generates a matching cURL command — handy for pasting into a shell, a CI script, or documentation. Headers are entered one per line as 'Name: value'; the body is sent as-is, and JSON bodies are detected so you can spot a malformed payload before sending.
See it in practice
Fetch a JSON resource — add an 'Accept: application/json' header in the tool.
- method
- GET
- url
- https://jsonplaceholder.typicode.com/todos/1
Frequently asked questions
Why does my request work in curl but fail here?
Almost always CORS. A browser enforces cross-origin rules and won't expose a response from a server that doesn't return the right Access-Control headers. curl and Postman aren't browsers, so they bypass this. For those APIs, use the generated cURL command from a terminal.
Is this a Postman replacement?
For quick, ad-hoc checks — yes. It covers methods, headers and bodies with zero setup. For collections, environments, scripting and team sharing, a full client like Postman still wins; this is the fast path, not the heavyweight one.
Are my requests or credentials stored?
The request runs from your own browser. Avoid putting long-lived secrets in shared examples, but for a one-off test the call goes directly from your machine to the target API.
How do I add multiple headers?
One per line, in 'Header-Name: value' form — for example 'Authorization: Bearer …' on one line and 'Content-Type: application/json' on the next.