AnyTool
Your files never leave your device. All processing happens locally in your browser.

How do I test a REST API in the browser?

Set the method, URL, headers, auth, and body, then send — AnyTool fires the request directly from your own browser via fetch() and shows the status, timing, headers, and pretty-printed response. It also generates copy-ready curl, fetch, Python, and 6+ more snippets live. No signup, no agent, and your tokens never touch a server.

  • All HTTP methods with headers, query params, and auth presets
  • Raw JSON, form, and multipart body with validation
  • Full response viewer: status, timing, size, headers, pretty body
  • Live code generation for curl, fetch, Python, Node, Go, and more
  • 100% client-side fetch — no signup, no desktop agent, private

What is

API Request Builder

An API request builder is a tool for composing and sending HTTP requests — choosing the method, URL, headers, authentication, and body — and inspecting the response. It is the core of API clients like Postman and Hoppscotch.

Developer Tools

Related terms

RESTHTTPcurlCORSPostman

How to Build and Send an API Request

Compose and send HTTP requests from your browser.

30 secWeb browser
  1. 1

    Set the request

    Pick a method, enter the URL, and add headers, auth, and a body.

  2. 2

    Send

    Send the request directly from your browser and inspect the response.

  3. 3

    Copy code

    Copy the request as curl or code in 9+ languages — generated locally.

Result: An HTTP response and code snippets

Frequently Asked Questions

No — the request fires from your own browser, so tokens never leave your device.

Unlike ReqBin or Postman Web (which run requests server-side or via a downloaded agent), AnyTool sends the request directly with the browser fetch() API. Your URL, headers, tokens, and body never touch our server — the trade-off is that cross-origin reads are subject to browser CORS.

CORS is a browser rule; copy the request as curl to run it where CORS does not apply.

A browser can only read a cross-origin response if the API allows your origin. When that fails, the tool shows a clear CORS explainer and a one-click "copy as curl/code" escape hatch so you can run the call from a terminal, plus an optional, off-by-default proxy field.

Yes — it live-generates curl, fetch, Python, Node, Go, and more as you type.

A live code panel regenerates runnable snippets in 9+ languages (curl, JS fetch, Node axios/fetch, Python requests, PHP, Java, Go, C#, Ruby) from your current request, all built locally.

Detailed Explanation

Methodology

How the API Request Builder Works

AnyTool composes an HTTP request — method, URL, query params, headers, auth (None/Basic/Bearer/API-key), and body (JSON/form/multipart) — and sends it directly from the user's browser with the native fetch() API, then renders the status, timing, size, response headers, and a pretty-printed body. A live panel regenerates runnable code (curl, JS fetch, Node, Python, PHP, Java, Go, C#, Ruby) from the current request via httpsnippet, all client-side.

  • All HTTP methods with headers, params, and auth presets
  • Request sent via browser fetch() — data stays on the device
  • Full response viewer: status, timing, size, headers, body
  • Live code generation in 9+ languages (httpsnippet)
  • Import/export curl; history stored locally
Limitations

Honest CORS Handling

Because the request fires from the browser, cross-origin reads are subject to the Same-Origin Policy: a response is only readable if the API returns permissive Access-Control-Allow-Origin. Rather than secretly routing through a server like ReqBin, AnyTool detects the CORS failure, shows a clear explainer, and offers a one-click "copy as curl/code" escape hatch plus an optional, off-by-default user-supplied proxy field.

Privacy & Security

Privacy vs Server-Side API Testers

Postman Web needs a downloaded Agent or metered Cloud Agent, and ReqBin and most "online API testers" run requests server-side, so your URL, headers, and tokens transit a third party. AnyTool keeps the request local: nothing is uploaded, there is no signup, and the builder plus code-gen work offline (only the actual send needs a network).

API Request Builder: AnyTool vs typical tools
CapabilityAnyToolTypical online testers
Where the request runsYour browser (fetch)Often a server
Account / agent neededNoOften yes
Code-gen targets9+ languagesVaries
CORS handlingHonest explainer + curlCryptic or hidden proxy
Offline builderYesNo

Capabilities reflect the live AnyTool tool; competitor behavior varies by service.