REST API Tester
A free browser-based HTTP client to test REST APIs, send HTTP requests (GET, POST, PUT, DELETE, PATCH), bypass CORS, and inspect response payloads.
A free browser-based HTTP client to test REST APIs, send HTTP requests (GET, POST, PUT, DELETE, PATCH), bypass CORS, and inspect response payloads.
This developer tool is built for fast, transparent API testing. Requests are forwarded through a stateless proxy solely to bypass browser CORS restrictions; your request data, headers, and tokens are never stored or logged on external servers. All request history remains saved directly in your browser.
REST - Representational State Transfer - is an architectural style that defines how systems communicate over HTTP. It's not a protocol or a library. It's a set of constraints: stateless communication, uniform resource URLs, and standard HTTP verbs (GET, POST, PUT, DELETE, PATCH) to express intent. When an architecture follows these constraints, we call it RESTful.
In my 15+ years of building distributed systems, REST APIs have been the backbone of virtually every product I've shipped — from internal microservices to third-party developer platforms. The beauty of REST is its simplicity: a URL identifies a resource, and the HTTP method tells the server what to do with it. GET /users/42 - fetches a user. DELETE /users/42 - removes them. No magic, no ceremony.
REST APIs power nearly everything you interact with online - payment gateways, social feeds, weather apps, authentication systems. If you're building or consuming web services, understanding REST isn't optional. It's foundational.
This REST API Tester is a browser-based HTTP client built for developers who need to debug, test, and inspect APIs without configuration overhead. You get the full picture of every request: status code, response time, response headers, and a syntax-highlighted JSON body — all within your browser.
It supports standard HTTP methods including GET, POST, PUT, DELETE, PATCH, and HEAD. You can add custom request headers (Authorization, Content-Type, X-API-Key), append query parameters, and craft JSON request bodies for POST and PUT calls. The response panel gives you the raw body, formatted JSON view, status code with color coding (green for 2xx, red for 4xx/5xx), and precise response timing in milliseconds.
Requests are forwarded through a stateless proxy server solely to bypass browser CORS restrictions; requests and headers are not stored or logged on our servers. Your request history remains saved directly in your browser's local storage for instant one-click replay.
Step 1
Enter the full API endpoint URL into the URL bar — make sure it starts with https:// or http://. If you're testing a public API, try https://jsonplaceholder.typicode.com/posts/1 to get started immediately.
Step 2
Select the HTTP method from the dropdown on the left — GET for fetching data, POST to create a resource, PUT to update, PATCH for partial updates, and DELETE to remove. If you're unsure, most read operations are GET.
Step 3
Switch to the Headers tab if your API requires authentication or content type — add Authorization: Bearer YOUR_TOKEN or Content-Type: application/json here. Most REST APIs need at least one header.
Step 4
For POST, PUT, or PATCH requests, switch to the Body tab and paste your JSON payload. Make sure it's valid JSON — the tool will highlight syntax errors before you send.
Step 5
Click Send Request. The response panel shows the HTTP status code (200 means success, 401 means unauthorized, 404 means not found, 500 is a server error), response time in milliseconds, all response headers, and the formatted JSON body. Use the Copy button to grab the response for use in your code.
Dedicated API platforms like Postman are powerful for team collaboration and extensive test suites, but setting up workspaces and collections can introduce unnecessary friction when you just need to inspect a quick endpoint. When you're in the middle of a focused debugging session and simply want to fire a GET or POST request to verify a response shape, a lightweight, instant browser-based client lets you test immediately without context switching or configuration overhead.
That's the exact problem this tool solves. Open a tab, paste a URL, hit Send. You have your response in seconds. No installation, no account creation, no project setup. Requests are forwarded through a stateless proxy solely to bypass browser CORS restrictions; your request data is not stored or logged on our servers, and your request history stays entirely in your browser.
I've found it especially useful in three scenarios: quickly verifying a third-party API's response shape before writing integration code, inspecting response headers and HTTP status codes, and validating that a newly deployed endpoint is returning expected status codes. If any of those sound familiar, this tool was made for you.
Zero install — runs directly in your browser with no account or setup required
Proxy-based CORS bypass — requests are forwarded, not stored, letting you test any public API safely
Local browser history — history stays in your browser with instant one-click replay
Needs internet connection — queries live external web APIs and remote endpoints in real time
Supports standard HTTP methods — GET, POST, PUT, DELETE, PATCH, and HEAD with complete header and body control
Syntax-highlighted responses — JSON output is auto-formatted and color-coded so you spot issues instantly
Response timing — see exact millisecond response times to catch slow endpoints before they hit production
One-click cURL export — easily copy requests as terminal cURL commands or client code snippets
Debugging backend endpoints during development
Verifying third-party API response structure before writing integration code
Testing authentication flows with Bearer tokens and API keys
Checking HTTP status codes after deploying a new endpoint
Inspecting response headers and HTTP status codes
Validating JSON request body formats for POST and PUT requests
Testing webhook endpoints by simulating incoming payloads
Quick API exploration without writing any code
Example Input
Method: POST
URL: https://jsonplaceholder.typicode.com/posts
Headers:
Content-Type: application/json
Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
Body:
{
"title": "Understanding REST API Design",
"body": "REST APIs should be stateless, resource-oriented, and use standard HTTP verbs correctly.",
"userId": 1
}Example Output
Status: 201 Created | Time: 143ms | Size: 218 B
Response Headers:
Content-Type: application/json; charset=utf-8
X-Powered-By: Express
Response Body:
{
"id": 101,
"title": "Understanding REST API Design",
"body": "REST APIs should be stateless, resource-oriented, and use standard HTTP verbs correctly.",
"userId": 1
}⚠Missing Content-Type header on POST requests
Best Practice: If your API returns 415 Unsupported Media Type, add Content-Type: application/json to your request headers.
⚠Testing localhost URLs
Best Practice: This tool uses a server-side proxy, so internal IPs like 127.0.0.1 and localhost are blocked for security. Use a public URL instead.
⚠Forgetting the Bearer prefix in Authorization headers
Best Practice: Use the correct format: Authorization: Bearer YOUR_TOKEN instead of sending only the token string.
⚠Invalid JSON in request body
Best Practice: Ensure all JSON strings use double quotes and remove any trailing commas before sending the request.
⚠HTTP vs HTTPS mismatch
Best Practice: If the API requires HTTPS and you use HTTP, you may get connection errors or redirect loops. Always use the protocol specified by the API.
HTTP Headers Cheatsheet
Complete guide to standard and security HTTP headers including Authorization, CORS control, caching policies, and CSP directives.
JWT
Syntaxes and patterns for JSON Web Tokens: structure (Header.Payload.Signature), signing keys, validation, claims (sub, exp, iat), and storage.
JSON Cheatsheet
Interactive reference guide for valid JSON syntax, data types, parsing/stringifying methods, schema validation rules, and language integrations.
cURL Cheatsheet
Essential cURL commands for making GET/POST requests, sending custom headers, form data, JSON payloads, authentication, and debugging connections.
Is this REST API Tester free to use?
Yes, completely free — no account, no subscription, no usage limits. Open the tool, paste your URL, send the request. That's it.
How does CORS bypass work and is it safe?
When your browser calls an API on a different domain, browser security (CORS) can block the request. Our tool routes your call through a server-side proxy, which makes the call on your behalf and returns the response. Your API key and request data are not logged or stored on our servers — the proxy is stateless and ephemeral.
Can I test APIs that require authentication?
Yes. Add your authentication header in the Headers tab — for JWT-based APIs use Authorization: Bearer YOUR_TOKEN, for API key authentication use whatever header the API specifies (X-API-Key, api-key, etc.). The tool sends your headers exactly as you enter them.
Why can't I test localhost or 127.0.0.1 URLs?
Because our proxy runs on a remote server, it cannot reach your local machine's localhost. To test local APIs, either expose them temporarily using a tunnelling tool like ngrok, or use curl directly in your terminal for local testing. This is a fundamental network constraint, not a limitation we can engineer around.
What is the difference between this tool and Postman?
Postman is a full API development platform with workspaces, automated testing, and team features. This REST API Tester is a focused, instant alternative: zero setup, open a tab, send a request, inspect the response. It is ideal for quick testing during active development.
Which HTTP methods does this tool support?
GET, POST, PUT, DELETE, PATCH, and HEAD. GET for reading, POST for creating, PUT for full replacement updates, PATCH for partial updates, DELETE for removal, and HEAD for inspecting response headers.
Is my API request data private?
Yes. Your request history is stored only in your browser's localStorage — it never leaves your machine. The proxy used for CORS bypass does not log request bodies, headers, or responses. If you're testing APIs with sensitive tokens or PII, clear your browser history after your session.
The response shows a 401 error — what does that mean?
401 Unauthorized means the API requires authentication and either you didn't provide credentials or the credentials are invalid. Check that you've added the Authorization header with the correct token format. If you just generated the token, double-check it hasn't expired — many JWTs have short TTLs (15 minutes to 1 hour).
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