API Request Tester
LiveFree online API tester — send HTTP requests and test REST APIs in your browser.
Understanding REST API Testing
Testing API endpoints is a daily activity for backend developers, frontend integrators, and QA engineers. Every API interaction involves an HTTP method (GET, POST, PUT, PATCH, DELETE), a URL, request headers (authentication tokens, content types, custom headers), and often a request body (JSON payloads, form data, file uploads). Verifying that an endpoint returns the expected status code, headers, and response body is essential before writing integration code, and catching issues at this stage prevents bugs from reaching production.
Use this free online API tester to send HTTP requests and test REST APIs directly in your browser. Send GET, POST, PUT, PATCH, and DELETE requests with custom headers, query parameters, and JSON body. View response status, headers, body, and timing. A lightweight Postman alternative — no installation required for API testing online.
The Devkitr API Request Tester sends real HTTP requests to any endpoint and displays the complete response — status code, headers, body, and timing information. Configure the HTTP method, add custom headers including Authorization tokens, set query parameters, and send JSON or form-encoded request bodies. The response is formatted and syntax-highlighted for easy inspection.
In a typical development workflow, API Request Tester becomes valuable whenever you need to free online api tester. Whether you are working on a personal side project, maintaining production applications for a company, or collaborating with a distributed team across time zones, having a reliable browser-based inspection tool eliminates the need to install desktop software, write one-off scripts, or send data to third-party services that may log or retain your information. Since API Request Tester processes everything locally on your device, your data stays private and your workflow stays uninterrupted — open a browser tab, paste your input, get your result.
Key Features
All HTTP Methods
Supports GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS methods, covering every standard REST API operation and preflight check.
Custom Header Management
Add, edit, and toggle request headers including Authorization (Bearer tokens, API keys), Content-Type, Accept, and any custom headers your API requires.
Request Body Editor
Write JSON, XML, form-urlencoded, or raw text request bodies with syntax highlighting and validation to catch payload errors before sending.
Response Timing Metrics
Displays total response time, helping identify slow endpoints and establish performance baselines during development and load testing.
How to Use API Request Tester
Enter the Endpoint URL
Type or paste the full API URL including protocol (https://), domain, path, and any query parameters.
Configure the Request
Select the HTTP method, add required headers (authentication, content type), and write the request body if needed.
Send the Request
Click send to execute the HTTP request. The tool makes the call and captures the complete response including redirects and error responses.
Analyze the Response
Review the status code, response headers, formatted body, and timing to verify the endpoint behaves as expected.
Use Cases
Prototyping API Integrations
Test third-party API endpoints with different parameters and headers before writing integration code to understand response shapes and error handling.
Debugging Authentication Flows
Send requests with Bearer tokens, API keys, or OAuth headers to verify authentication is working and identify where token validation fails.
Verifying CRUD Operations
Test the complete lifecycle of a resource — create with POST, read with GET, update with PUT/PATCH, delete with DELETE — against your backend.
Reproducing Bug Reports
Reconstruct the exact API call from a bug report (method, headers, body) to reproduce the issue in isolation without running the full application.
Pro Tips
Save frequently used requests (headers, auth tokens, base URLs) in a text file for quick copy-paste during iterative testing sessions.
Always test error cases explicitly — send invalid JSON, wrong auth tokens, and missing required fields to verify your API returns proper error responses.
Use the OPTIONS method to check CORS preflight responses when debugging cross-origin issues in browser-based frontend applications.
Compare response times across multiple requests to establish performance baselines — a single slow response may not indicate a real problem.
Common Pitfalls
Testing only the happy path and ignoring error responses
Fix: Test 400, 401, 403, 404, and 500 responses explicitly. APIs should return meaningful error messages, proper status codes, and consistent error formats.
Forgetting to set Content-Type header for POST/PUT requests
Fix: Most APIs require Content-Type: application/json for JSON bodies. Missing this header often causes 415 Unsupported Media Type or silent request body parsing failures.
Using production API keys in testing without rate limit awareness
Fix: Use test or staging API keys when available. Production keys may have rate limits, and excessive testing can exhaust quotas or trigger blocking.
Frequently Asked Questions
QWhat is this online API tester?
A free, browser-based API testing tool that lets you send HTTP requests (GET, POST, PUT, DELETE), set headers, add JSON body, and inspect full responses — like Postman but with no installation.
QCan I test REST APIs online for free?
Yes. This API tester is completely free. Send requests to any REST API endpoint, view response status, headers, body, and timing — all in your browser.
QDoes the API tester support authentication?
Yes. Add Authorization headers (Bearer tokens, Basic auth) or custom headers for any authentication scheme in your API requests.
QAre there CORS limitations?
Browser-based API testing is subject to CORS policies. APIs that do not allow cross-origin requests may be blocked by the browser.
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