Online API Tester — Free REST API Testing Tool (No Signup)

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Features & Tips

• Support for all HTTP methods (GET, POST, PUT, DELETE, etc.)
• Custom headers with add/remove functionality
• Multiple body types: JSON, form data, plain text
• Real-time response with syntax highlighting

• Request/response history with timestamps
• Save and load frequently used requests
• Response time measurement
• Export history as JSON for backup

About the Online API Tester

Building or debugging an API usually means reaching for a heavyweight desktop client, creating an account, and installing yet another app just to fire off a single GET request. The Online API Tester skips all of that: it's a browser-based REST client for sending GET, POST, PUT, and DELETE requests and inspecting the response the moment it comes back. It's built for the quick, everyday checks developers actually do — confirming an endpoint returns the right JSON, checking that a POST body is validated correctly, or verifying a status code after a backend deploy — without the overhead of a full API platform.

Each request lets you set the HTTP method, target URL, custom headers, and a request body, so you can replicate real-world calls: pass an Authorization header with a bearer token, set Content-Type to application/json, or send form data to a webhook. Once you send the request, the tool displays the response instantly, so you can check status codes, headers, and payload structure in the same view without switching tabs or writing a single line of code. Because it supports all four core HTTP verbs, it covers the typical CRUD cycle — reading a resource, creating one, updating it, and deleting it — using the same interface.

Everything runs client-side in your browser, so there's nothing to install and no account to create before you can test an endpoint. This also makes it a convenient way to double-check an API from any machine — at your desk, on a laptop between meetings, or while reviewing a colleague's endpoint — without depending on locally installed software. Keep in mind that requests are still subject to the target server's CORS policy, so testing an API that hasn't enabled cross-origin requests from a browser may return a CORS error rather than the expected response.

How to Test a REST API Endpoint

Send a request to any REST API endpoint and inspect the response directly in your browser.

Choose the HTTP method

Select GET, POST, PUT, or DELETE depending on the operation you want to test.

Enter the endpoint URL

Type or paste the full API URL you want to send the request to.

Add custom headers (optional)

Add any headers the endpoint requires, such as Authorization or Content-Type.

Add a request body (optional)

For POST or PUT requests, enter the JSON or form data payload you want to send.

Send the request

Click send to fire the request from your browser to the target endpoint.

Review the response

Check the returned status code, headers, and response body displayed instantly on the page.

Frequently Asked Questions

What HTTP methods does the API tester support?

The tester supports all standard HTTP methods: GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS. You can set request headers, query parameters, and a request body (JSON, form data, or plain text).

Can I save and reuse API requests?

Yes, you can save requests to a collection and reload them later. Saved requests remember the URL, method, headers, and body, so you can quickly re-run tests without re-entering all parameters.

How do I handle authentication in the API tester?

Add an Authorization header with your token (e.g., Bearer <token> for JWT) in the Headers tab. For Basic Auth, add an Authorization header with Base64-encoded "username:password". API key authentication is usually done via a custom header or query parameter specified by the API.