GammaRay is a mature runtime introspection and debugging tool for Qt applications, developed by KDAB. It injects a probe into a target Qt process via mechanisms such as LD_PRELOAD, debugger scripts, or Windows DLL injection, then exposes the target's QObject tree, properties, signals/slots, widgets, QML scenes, models, timers, network activity, state machines, and paint operations over a custom client-server protocol. The client is a Qt Widgets GUI that can connect locally or remotely, while the launcher handles process discovery, ABI detection, injection, and self-tests. The codebase is organized into shared protocol infrastructure, core probe/server logic, client-side remote proxies, UI tool factories, and more than 30 plugin-based inspectors. Architecturally, each tool follows an interface/client/server triad: a common interface defines the contract, a client proxy handles remote communication, and a server-side implementation performs the actual introspection. ObjectBroker provides cross-process object registration, RemoteModelServer and RemoteModel synchronize Qt model/view data, and PropertySyncer mirrors property state bidirectionally. Key entry points include client/main.cpp, launcher/app/main.cpp, launcher/cli/main.cpp, core/probe.cpp, and core/tools/objectinspector/objectinspector.cpp. The build is CMake-based with Conan recipes, and the repository includes an extensive QTest suite and GitHub Actions workflows for Qt 5/6, mingw, sanitizers, and documentation. The project is actively maintained, but it deliberately reaches into Qt private headers (e.g., qobject_p.h, qqml context/data headers, qpaintbuffer_p.h) and vendors substantial third-party code such as KUserFeedback, backward-cpp, and KDE model helpers. This makes the codebase sensitive to Qt version changes and adds maintenance complexity. Despite that, the architecture is coherent, the plugin boundaries are clean, and many components are general enough to be reused independently in other Qt applications.