The memory allocator project is the simplest way to show that I am comfortable close to the machine. I implemented malloc, free, and realloc around block metadata, linked-list management, integrity checks, and a test suite.
This kind of project changes how you read memory bugs. Allocation is not magic anymore. You see where metadata lives, how fragmentation appears, why double-free and corruption bugs are dangerous, and why C code needs boring defensive checks.
I use this project as evidence for software security, embedded security, and low-level systems roles. It is not a cybersecurity product, but it is cybersecurity-adjacent in the right way: it teaches the failure modes attackers rely on.