When most people picture web testing, they imagine someone clicking through a web page, filling out forms, and seeing if a button works. But modern web development isn't happening on the surface anymore. The real application lives beneath the UI—in a web of REST, GraphQL, and microservice APIs connecting databases, cloud functions, and third-party services. When a bug manifests on a webpage, it’s usually just a symptom. The root cause almost always lives deep down in an API response or a security oversight. Let’s step past basic functional checks and take a deep, practical dive into the most elusive, critical bugs found in API and Security Testing—how they happen, how to find them, and how to report them like a seasoned QA engineer. Part 1: Anatomy of an API Bug API bugs are inherently quiet. They don't throw colorful browser alerts or misalign CSS buttons. They operate in raw HTTP response payloads, headers, and status codes. Here are the three most critical categories of API ...
QA Cosmos is a complete blog for software testers. We share tutorials, tools, tips, and guides on manual testing, automation (Selenium, Playwright), bug tracking, interview questions, and QA career growth.