While simple, osx "leaks" is truly formidable because you can call it while a program that was compiled without any special flag is running. For example the Redis testing framework runs "leaks" every time an unit was executed completely, warning the user if a leak is found. When this happens I resort to valgrind to find the cause, but to call "leaks" every time you want during development and having it running in a few seconds is a killer feature. I miss it when I develop using Linux.