API Tester

About the Tool

Debugging endpoints shouldn't require a 300MB download and a forced account login. This online api tester is a lightweight, browser-based HTTP client that lets you test REST APIs instantly. Whether you are building a new backend, integrating a third-party service, or just verifying payload structures, this tool gives you raw access to send requests and inspect responses without the friction of desktop software.

I built this because half the time, developers just need to fire off a quick GET or POST request to see what comes back. You get the power of a dedicated HTTP client—custom headers, query builders, and JSON highlighting—packaged into a single, lightning-fast web interface.

How to Use

Testing your endpoints takes less than ten seconds. Here is how you send your first request.

1. Drop in your endpoint: Paste your API URL into the main address bar. You can also click one of the "Quick Presets" to load a working example immediately.
2. Select the method: Choose your HTTP method (GET, POST, PUT, PATCH, DELETE) from the dropdown next to the URL.
3. Configure headers & params: If you need an auth token or custom query strings, jump into the Headers or Params tabs. The tool automatically encodes your query strings.
4. Add your payload (if needed): For POST or PUT requests, switch to the Body tab. Drop your JSON in and hit the "Beautify JSON" button to format it properly.
5. Fire the request: Click Send. The tool routes your call and instantly displays the status code, response time, and the highlighted JSON response body.

Privacy & Security

Here's the thing — API keys and bearer tokens are sensitive. When you use this api tester, your session data stays private.

We do not log your request payloads, endpoints, or API keys in a database. Your history is stored strictly in your browser's local session and vanishes the moment you close the tab. To bypass strict CORS errors that block normal browser requests, your calls route through a secure, ephemeral server-side proxy. The proxy acts as a pass-through and immediately discards your data once the response hits your screen. You get the freedom to test secure endpoints safely.

Features

I cut out the enterprise bloat and kept exactly what you actually use to debug APIs.

• Complete HTTP Support: Send GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS requests effortlessly.
• Intelligent Query Builder: Stop manually encoding URLs. Add key-value pairs in the Params tab, and the tool builds the query string dynamically.
• Header Management: Inject custom headers, Bearer tokens, and Content-Type declarations with simple toggle switches.
• Response Insights: Instantly see the HTTP status code (color-coded for success or failure), the response time in milliseconds, and the exact payload size.
• JSON Auto-Formatting: The body editor comes with a one-click beautifier, and the response window automatically color-highlights valid JSON for easy reading.

Technical Specifications

For those who want to know how the request engine operates under the hood.

Postman vs Our Tool: Why Choose Ours?

Postman is a fantastic enterprise tool, but it has grown heavy. If you manage massive team workspaces, complex CI/CD pipelines, or automated test suites, stick with Postman. But if you just want to test an endpoint right now without signing in, syncing workspaces, or waiting for a bloated electron app to load, this online api tester is your answer.

Our tool requires zero installation and loads in milliseconds. It handles CORS issues automatically via a background proxy, meaning you get desktop-level request power straight from your browser tab. Use it when you need speed, simplicity, and immediate results.

When the Browser Blocks You Instead

This tool proxies your request, so cross-origin rules never get in the way here. Your own app is a different story — the browser will enforce them there.

That gap catches people out. A request that works in this tester can still fail from your frontend, because we are not subject to the Same-Origin Policy and your page is. Our CORS header tester checks that side specifically, sending a real preflight and naming the failing check.

If you have already hit the error, fixing a failing CORS preflight covers the five causes we see most.