API Testing Articles

Learn how to test GraphQL APIs using Fiddler: capture, inspect, modify, and replay queries with HTTPS decryption, AutoResponder, and Composer. A practical fiddler tutorial for developers and QA engineers.

Master API endpoint testing with Fiddler Composer: step-by-step guide covering HTTPS decryption, auth headers, multipart forms, and real-world debugging for developers and QA engineers.

Learn how to debug OAuth 2.0 authorization code, PKCE, and token flows in real time using Fiddler’s HTTPS decryption, filtering, and scripting features.

Learn how to debug OAuth 2.0 flows end-to-end using Fiddler: HTTPS decryption, JWT inspection, PKCE validation, and request replay for API testing.

Learn how to automate API tests using Fiddler's AutoResponder, Custom Rules, Composer, and HTTPS decryption — a practical guide for developers and QA engineers.

Learn how to automate API tests using Fiddler Classic’s AutoResponder, FiddlerScript, and HTTPS decryption — no external tools required. Practical, step-by-step guide for developers and testers.

Learn how to capture, inspect, modify, and troubleshoot WebSocket APIs using Fiddler — with HTTPS decryption, frame filtering, and scripting tips.

Learn how to use Fiddler Composer for precise, repeatable API endpoint testing—with HTTPS decryption, dynamic headers, auth flows, and real-time debugging.