API Tester
Free online API Tester. Send HTTP requests (GET, POST, PUT, DELETE) and inspect responses directly in your browser.
What is the API Tester?
The API Tester is a free, browser-based HTTP client that lets you send API requests (GET, POST, PUT, PATCH, DELETE) and inspect the full response — status code, headers, body, and response time — without installing Postman or any other desktop software. It works like a lightweight version of Postman, directly in your browser.
This tool supports custom request headers, JSON request bodies, automatic JSON formatting of responses, and measures response time in milliseconds. It is ideal for quickly testing REST APIs, debugging webhooks, and verifying endpoint availability.
How to Use the API Tester
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1
Enter the API URL
Type or paste the endpoint URL. The tool automatically adds
https://if not specified. -
2
Select HTTP Method
Choose GET, POST, PUT, PATCH, or DELETE from the dropdown. For POST/PUT/PATCH, a body editor appears where you can enter JSON data.
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3
Add Headers (Optional)
Add authentication tokens, content types, or any custom headers using the key-value editor.
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4
Send and Inspect
Click Send to fire the request. The response displays with status code (color-coded), response time, body size, headers, and a formatted response body.
Real-World Use Cases
REST API Testing
Quickly test your REST API endpoints during development without switching to Postman or writing cURL commands. Verify response structure and status codes.
Webhook Debugging
Send test payloads to webhook endpoints to verify they accept and process incoming data correctly.
Third-Party API Exploration
Explore public APIs (JSONPlaceholder, OpenWeather, etc.) to understand their response format before writing code.
⚠️ Important: CORS Limitations
Since this tool runs in your browser, some APIs may block requests due to CORS (Cross-Origin Resource Sharing) policies. APIs must include Access-Control-Allow-Origin headers to allow browser-based requests. Public APIs like JSONPlaceholder work perfectly. For private APIs, consider using a CORS proxy or test locally with browser CORS disabled in development mode.
Frequently Asked Questions
Why do some API requests fail with a CORS error?
CORS (Cross-Origin Resource Sharing) is a browser security feature that blocks requests to APIs that don't explicitly allow browser-based access. The API server must send proper CORS headers. This is a browser limitation, not a tool limitation.
Is this tool free to use?
Yes, completely free with no usage limits, no account required, and no rate limiting. You can send as many requests as you need.
Are my API requests logged or stored?
No. All requests are made directly from your browser to the target API. Nothing is routed through or stored on our servers. Your API keys and data remain private.
Can I send authenticated requests?
Yes. Add an Authorization header with your Bearer token, API key, or Basic auth credentials using the custom headers editor.
How is this different from Postman?
This is a lightweight, zero-install alternative for quick API testing. Postman offers more advanced features like collections, environments, and scripting. Use this tool for quick one-off tests and Postman for complex API workflows.