frida-gum is the core instrumentation engine of the Frida reverse-engineering framework. It is a cross-platform C library that provides dynamic binary instrumentation: function hooking/interception, instruction-level tracing (Stalker), memory access monitoring, and a JavaScript runtime (GumJS) for scripting. The library operates at the assembly level with architecture-specific backends for x86, x86-64, ARM, ARM64, and MIPS, and platform modules for Linux, macOS, Windows, iOS, Android, and QNX. It is not a standalone application but a library consumed by frida-core; it exposes a GObject-based C API plus JavaScript and C++ bindings.