API Endpoint Tester
Free online tool to test REST API endpoints with GET, POST, PUT, DELETE methods—add headers, bodies, and inspect full responses instantly.
Our API endpoint tester is a free, browser-based utility for developers to send HTTP requests and analyze responses without installations. Ideal for debugging, prototyping, or learning REST APIs, it supports custom methods, authentication, and detailed output viewing—all processed client-side for speed and privacy.
Common Use Cases for API Testing
- ✓API Debugging
Quickly test endpoints during development to verify responses, status codes, and data flow in Node.js or React apps.
- ✓Integration Testing
Simulate requests with custom headers and bodies to ensure third-party API integrations work seamlessly.
- ✓REST Learning
Practice HTTP methods (GET/POST) and authentication (Bearer tokens) for beginners building web services.
- ✓Microservices Validation
Send PUT/DELETE requests to confirm data mutations across services in Docker or Kubernetes environments.
- ✓Frontend API Calls
Mock backend responses to test UI interactions without a full server setup during prototyping.
- ✓Compliance Checks
Inspect CORS headers and rate limits on public APIs to ensure adherence to standards like OAuth.
Why Choose Our API Tester?
Full HTTP Methods
Supports GET, POST, PUT, DELETE, PATCH, and HEAD for comprehensive REST API testing
Custom Headers & Auth
Add arbitrary headers, Authorization (Basic/Bearer), and query params effortlessly
Request Body Options
Send JSON, form-data, raw text, or XML bodies with syntax highlighting for easy editing
Response Inspection
View status codes, response headers, timings, and body with auto-formatting (JSON/XML)
Request History
Save and replay recent requests in-browser for iterative testing sessions
Client-Side Execution
All requests processed via browser Fetch API—no proxy servers—keeping it lightweight and private
How to Use the API Endpoint Tester
- Enter URL: Input the API endpoint (e.g., https://api.example.com/users)
- Select Method: Choose GET, POST, PUT, DELETE, or others from the dropdown
- Add Params/Headers: Include query strings, custom headers like Content-Type: application/json
- Body (if needed): For POST/PUT, enter JSON or form data in the editor
- Send & Review: Click send to view response status, headers, body, and timings
Understanding API Request/Response Flow
An API request follows HTTP standards: method + URL + headers + body → server processes → response with status (200 OK, 404 Not Found), headers (CORS, Cache-Control), and body (JSON data).
Example: GET https://jsonplaceholder.typicode.com/posts/1 returns 200 with user data. This tool simulates via Fetch, respecting CORS policies.
- Status Codes: 2xx success, 4xx client error, 5xx server error—decoded with explanations
- Headers: Inspect Set-Cookie, Location, or custom metadata
- Body Parsing: Auto-highlights JSON; supports binary previews for images/blobs
Useful for regex like /^https?:\/\/.*$/ on URLs or validating JSON responses in your scripts.
Advanced Features & Capabilities
CORS Handling
Tests preflight OPTIONS and handles Access-Control-Allow-Origin for cross-origin APIs.
Error Simulation
View network errors, timeouts, or invalid responses with stack traces for robust debugging.
Export Requests
Copy cURL commands or HAR files for sharing tests with teams or importing into Postman.
Frequently Asked Questions
What HTTP methods does the API tester support?
The tool supports all common REST methods: GET, POST, PUT, DELETE, PATCH, and HEAD, allowing full CRUD operations on your endpoints.
Is it secure to test sensitive APIs here?
Requests run client-side using your browser's Fetch API, so tokens and data stay local. Avoid testing production secrets; use for dev/staging only.
Can I test APIs with authentication?
Yes, add Authorization headers for Bearer tokens, API keys, or Basic auth. The tool handles CORS if the API allows browser origins.
What response formats are displayed?
Responses show status code, headers, and body with auto-detection for JSON (pretty-print), XML, or plain text. Timings and size metrics included.
Does it support file uploads?
Currently focused on text-based bodies; for multipart/form-data with files, use browser dev tools or desktop clients like Postman for advanced needs.
Is there a limit on request size?
Browser constraints apply (e.g., ~2MB for bodies), but it's suitable for most API testing. For bulk data, consider server-side tools.
Security & Privacy Considerations
This API tester emphasizes secure, private testing practices:
- Local Execution: Requests use your browser's network—no data routed through our servers
- CORS Compliance: Respects API policies; can't bypass restrictions intentionally
- Best Practices: Use dev tokens only; monitor for rate limits to avoid API abuse
- Related Security: Integrate with JWT Decoder for auth token inspection
Integration & Code Examples
Replicate tests in JavaScript using Fetch or Axios for automated scripts:
JavaScript Example (Fetch API):
// Example POST request to test an API endpoint
fetch('https://jsonplaceholder.typicode.com/posts', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Authorization': 'Bearer your-token'
},
body: JSON.stringify({
title: 'Test Post',
body: 'API tester integration',
userId: 1
})
})
.then(response => response.json())
.then(data => console.log('Response:', data))
.catch(error => console.error('Error:', error));