API Request Tester
Lightweight Postman alternative. Test REST APIs with custom headers and JSON payloads locally.
What is an API Request Tester?
An API request tester (also called a REST client or HTTP client) lets you send HTTP requests (GET, POST, PUT, DELETE, PATCH) to any API endpoint and inspect the response. Think of it as a lightweight alternative to Postman or Insomnia that runs directly in your browser. Our free online API tester supports custom headers, JSON request bodies, query parameters, and displays formatted response data with status codes and timing information.
How to Test a REST API Online
- 1Enter the API URL
Type or paste the full API endpoint URL into the URL field.
- 2Select HTTP method
Choose GET, POST, PUT, DELETE, or PATCH from the method dropdown.
- 3Add headers and body
Add custom headers (like Authorization or Content-Type) and a JSON request body if needed.
- 4Send and inspect
Click "Send" to execute the request. View the response status, headers, body, and response time.
Frequently Asked Questions
Is this a Postman alternative?
Yes! DevDeck API Tester is a lightweight browser-based alternative to Postman. It supports all common HTTP methods, custom headers, and JSON payloads without requiring any download or account.
Can I test APIs that require authentication?
Yes. You can add Authorization headers (Bearer tokens, API keys, Basic auth) in the headers section. Since everything runs in your browser, your credentials are never stored on any server.
Does it support CORS?
Browser-based API testing is subject to CORS restrictions. If the target API does not allow cross-origin requests, you may need to use a CORS proxy or test from the API's own domain.
Can I save and reuse requests?
Currently, requests are stored in your browser session. You can use the Activity tray to view recent requests.
Why Use DevDeck?
Most API testing tools require installing desktop apps or creating accounts. DevDeck API Tester runs instantly in your browser with zero setup. Your API keys and tokens never leave your device.