The new Release 20.03 is out! You can download binaries for Windows and many major Linux distros here .
I have found DrMemory to be very useful. You install it, drag your .exe onto its icon, and after closing your app, it reports any issues in Notepad.Home page:http://drmemory.org/
Even though it doesn't support C++'s new and delete allocation/de-allocation mechanisms, I've been using MemWatch for several years.