API Tester — Free Online REST API Client & HTTP Request Builder

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API Tester_
Send HTTP requests · Test any REST API with headers, body & auth — directly from your browser
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Body
Headers
Response will appear here after sending a request
About · FAQ · How it works

Free Online API Tester — Test REST APIs Instantly

This free API testing tool lets you send HTTP requests to any REST API endpoint and inspect the response — all from your browser. Whether you need to test a GET endpoint, debug a POST request, or verify webhook payloads, this tool handles it with zero setup.

Lightweight Postman Alternative — No Install, No Signup

Postman, Insomnia, and Thunder Client are powerful API clients, but they require installation, account creation, and cloud sync. For quick API tests during development, this browser-based API tester is faster to reach and simpler to use. No desktop app, no Electron overhead, no account required.

Full HTTP Request Builder

Build complete HTTP requests with custom headers, JSON or text request bodies, query parameters, and authentication (Bearer token, Basic auth). Supports all standard HTTP methods: GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS. View formatted JSON responses, response headers, status codes, and precise timing.

Privacy-First API Testing

Unlike cloud-based API tools that route your requests through proxy servers, this tool sends requests directly from your browser using the Fetch API. Your API keys, tokens, and request data never leave your machine. No data is logged, stored, or transmitted to any third-party server.

Developer Workflow Integration

Copy any request as a cURL command for terminal use or documentation. Share request configurations via URL. Request history keeps track of your recent API calls during your session. Format and syntax-highlight JSON responses automatically for easy inspection.

Frequently Asked Questions — API Tester

What is an API tester?

An API tester is a tool that lets you send HTTP requests (GET, POST, PUT, PATCH, DELETE) to any API endpoint and inspect the response. It is essential for developers building, debugging, and testing REST APIs, webhooks, and web services.

Is this API tester free?

Completely free — no account, no subscription, no ads, no data collection. Unlike Postman which requires account creation, syncs data to the cloud, and paywalls collaboration features, this tool runs entirely in your browser.

Does this tool send requests from my browser?

Yes. Requests are sent directly from your browser using the Fetch API. This means CORS restrictions apply — if the target API does not allow cross-origin requests from browsers, you may see a CORS error. Your API keys and data never touch our servers.

What HTTP methods are supported?

GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS. You can set custom headers, add a JSON or text request body, configure Bearer token or Basic authentication, and build query parameters with a visual editor.

Can I set custom headers and authentication?

Yes. Add any number of custom headers as key-value pairs. For authentication, use Bearer token (API key) or Basic auth (username and password). The Authorization header is automatically constructed and sent with your request.

Can I see response headers and timing?

Yes. The response panel shows the HTTP status code, status text, response time in milliseconds, response size, and all response headers. The response body is automatically formatted if it is JSON.

How does this compare to Postman or Insomnia?

Postman and Insomnia are desktop apps that require installation and account creation. Postman syncs your data to their cloud by default. This tool is a lightweight browser-based alternative — no install, no account, everything stays local. Perfect for quick API tests without the overhead of a full desktop app.

Can I copy requests as cURL commands?

Yes. After building your request, click the "Copy as cURL" button to get a ready-to-paste cURL command. This is useful for sharing with teammates, pasting into terminals, or embedding in documentation.

Request History ✕ Close