An API tester lets you send HTTP requests to any endpoint and inspect the response — headers, status code, body, and timing. It's the primary tool for exploring API behavior, debugging integration issues, and verifying authentication flows.
When working with web scraping APIs like AlterLab, you'll typically send POST requests with a JSON body specifying the target URL and extraction parameters. The API returns a JSON response with the extracted data, metadata (status code, headers, timing), and any error information.
Understanding HTTP fundamentals — request methods (GET, POST, PUT, DELETE), headers (Authorization, Content-Type, Accept), status codes (200, 400, 401, 429, 500), and authentication patterns (API keys, Bearer tokens, OAuth) — is essential for effective API integration and debugging.