API Tester
FreeSend HTTP requests to any API endpoint and inspect the response, right in your browser.
Runs entirely in your browser. Requests go directly from your browser to the target API.
History
No requests yet.
Recent Activity
Visible to everyone. Last 20 uses across all visitors, newest first.
GET -- 200
1 month ago
GET -- 200
1 month ago
What this tool does
This tool sends HTTP requests to any API endpoint and shows you the response, right in your browser, with support for custom headers, JSON/form/text bodies, Bearer/Basic/API Key authentication, and a short request history.
How It Works
When you press Send, this tool builds a standard browser fetch() request from your chosen method, URL, headers, authentication, and body, then sends it directly from your browser to that URL, timing the response and measuring its size. Because there is no server in between, the request is subject to the same-origin and CORS rules every browser enforces, an API must send Access-Control-Allow-Origin headers for its response to be readable from a page on a different origin, otherwise the browser blocks it before this tool ever sees the response.
Problems it solves
- Quickly checking what a REST API endpoint returns without installing a separate app.
- Testing different authentication methods against an API you are integrating with.
- Inspecting response headers, status codes, and timing for debugging.
- Re-running a recent request with small tweaks using the built-in history.
Frequently asked questions
›Why did my request fail with no useful error?
This is almost always CORS. Browsers block cross-origin responses unless the target API explicitly allows your origin via an Access-Control-Allow-Origin header, and when that happens the browser hides the response entirely for security reasons, showing only a generic network error.
›Is my data sent anywhere besides the API I am testing?
No. This tool has no backend of its own, your browser sends the request directly to the URL you enter, the same way any web page or app would. Nothing passes through this site's servers.
›What is the difference between Bearer, Basic, and API Key auth?
Bearer sends a token in an Authorization header, common for OAuth2 and JWT-based APIs. Basic Auth sends a base64-encoded username and password. API Key auth sends your key in a custom header name that the API defines, such as X-API-Key.
›Why does GET not let me set a body?
Per the HTTP specification, GET (and HEAD) requests are not expected to carry a request body, and the Fetch API used by this tool will not attach one for those methods. Switch to POST, PUT, PATCH, or DELETE if you need to send a body.
›Does the history save between visits?
No, the last 10 requests are kept only for your current page session and are cleared when you reload or leave the page, nothing is stored permanently.
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