REST API Client
Send HTTP requests and inspect responses — a lightweight Postman alternative in your browser
This tool runs in the browser. APIs that do not allow CORS cannot be called.
Response
What is REST API Client?
REST API Client is a free browser-based tool for sending HTTP requests and inspecting responses, serving as a lightweight alternative to Postman. It supports all HTTP methods (GET, POST, PUT, PATCH, DELETE), custom headers, query parameters, request bodies, and SSE streaming. View response status codes, headers, body, and timing information. Request history is saved locally for quick re-use. All requests go directly from your browser to the target server - this tool does not proxy or store your data. Essential for API development, testing, and debugging.
How to Use
- Enter the API URL and select the HTTP method.
- Add query parameters or headers if needed.
- For POST/PUT requests, enter the request body.
- Click Send to make the request and view the response.
Tips & Best Practices
- Use the 'Try it' button with pre-configured examples to quickly understand the tool's features.
- Add Authorization headers for testing authenticated APIs (Bearer tokens, Basic auth, API keys).
- Enable SSE streaming to test AI API endpoints that return streaming responses.
- Check the request history to quickly re-send previous requests without re-entering details.
- If you get CORS errors, the target API does not allow browser requests. Use a proxy or test from the server side.
Use Cases
API Development
Test your REST APIs during development by sending requests and inspecting responses.
Integration Testing
Verify third-party API endpoints before writing integration code.
Debugging
Diagnose API issues by inspecting response headers, status codes, and body content.
AI API Testing
Use SSE streaming to test ChatGPT, Claude, and other AI API streaming endpoints.
FAQ
Why do some APIs return CORS errors?
CORS (Cross-Origin Resource Sharing) is a browser security policy. APIs must explicitly allow cross-origin requests. This tool runs in your browser, so APIs without CORS headers will be blocked.
What APIs can I test?
Any API that allows CORS, such as jsonplaceholder.typicode.com, httpbin.org, and most public APIs with CORS enabled.
What is SSE (Server-Sent Events)?
SSE is a standard that allows a server to push real-time updates to a browser over HTTP. It's commonly used for AI API streaming responses, live feeds, and notifications. Enable the Stream toggle to receive streaming responses.
What is a REST API?
REST (Representational State Transfer) is a web service architecture style based on HTTP that uses methods like GET, POST, PUT, and DELETE to perform CRUD operations on resources.
Is my request data stored on this site's server?
No, API requests are sent directly from your browser to the target server. This site does not store or relay your request data.
What should I do if I get a CORS error?
CORS errors occur when the target server does not allow direct requests from browsers. You need to configure CORS headers on the server side or use a separate proxy.
Can I test APIs that require authentication?
Yes, you can test authenticated APIs by adding an Authorization token (Bearer, Basic, etc.) in the headers.
Is my request data stored on this site?
No, API requests go directly from your browser to the target server. This site does not store or relay your data.
What is SSE streaming?
SSE (Server-Sent Events) is a standard for receiving real-time updates from a server over HTTP. Enable the Stream toggle for streaming responses.
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