API Debugger
Test and inspect REST APIs directly from your browser
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This request does not include a body payload.
Direct sends from your browser; Proxy routes via the server to bypass browser CORS headers.
Follows HTTP redirects up to 5 hops with SSRF inspection on each hop.
Disabled by default for safety. When unchecked, tokens are stripped before saving to localStorage.
Click "Send" to execute request and inspect the response.
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Preview not available.
How to Test and Debug REST APIs
Testing and debugging RESTful APIs is an essential part of modern web and mobile application development. With our free online API Debugger, you can test endpoints, verify payload structures, check response headers, and generate integration code without leaving your browser.
1. Select HTTP Method
Choose from GET, POST, PUT, PATCH, DELETE, HEAD, or OPTIONS depending on the CRUD operation you want to perform.
2. Add Query Parameters & Headers
Use the intuitive Key/Value editors to manage query strings and headers like Accept, Content-Type, or custom API tokens.
3. Configure Payloads & Auth
Pass JSON data, URL-encoded forms, or multipart data with built-in JSON validation and Bearer / Basic / API-Key authentication.
4. Inspect Response & Code
Review formatted JSON with syntax highlighting, examine latency metrics, or export ready-to-use code in Python, JavaScript, PHP, and Go.
Frequently Asked Questions
What is an API Debugger?
An API Debugger is an interactive developer tool used to compose, send, and inspect HTTP requests (GET, POST, PUT, PATCH, DELETE) to REST APIs. It allows developers to verify status codes, examine response payloads (JSON, XML, HTML), validate request headers, debug authentication tokens, and diagnose network issues directly without writing code.
How do I test a REST API online?
To test a REST API, select your desired HTTP method (e.g., GET or POST), enter the target endpoint URL, configure any query parameters, headers (such as Content-Type or Authorization), and provide a request body if sending data. Click Send to trigger the request and inspect the response headers, timing, and formatted JSON output.
How do I send a GET request?
Select "GET" in the method dropdown, paste the API endpoint URL (for example, https://jsonplaceholder.typicode.com/users), add any optional query parameters in the Params tab, and click Send. The API Debugger will retrieve and display the requested resources.
How do I test a POST request with JSON payload?
Select "POST" in the method selector, enter your endpoint URL, navigate to the Body tab, select JSON format, paste your JSON data structure, and click Send. The debugger automatically sets Content-Type to application/json and validates your JSON syntax prior to transmission.
How do I inspect API response headers?
After executing any request, switch to the "Headers" tab inside the Response panel. You will see all returned response headers including Content-Type, Cache-Control, Server, ETag, Rate-Limit information, and CORS configuration.
What causes a 401 Unauthorized API error?
A 401 Unauthorized error indicates that the target API endpoint requires authentication credentials that were missing or invalid. Use the Auth tab in this API Debugger to supply a Bearer Token, Basic Auth credentials, or an API Key header.
What is a 404 Not Found API error?
A 404 Not Found error means the server cannot locate the requested URI. Verify that your endpoint path, route parameters, and base URL are spelled correctly without trailing slash discrepancies.
What does a 500 Internal Server Error mean?
A 500 Internal Server Error indicates an unhandled exception or crash occurred on the destination API server. Inspect the raw response body in the debugger to see if the server provided diagnostic error details or stack traces.
How can I test APIs directly in the browser without installing Postman?
Our browser-based API Debugger runs instantly without requiring desktop app downloads, account logins, or browser extensions. It includes automatic CORS detection, a secure server proxy fallback, cURL import/export, and code snippet generation in 9 programming languages.