The _<I>Mergeall_</I> content sync/backup system, available at this
_<A HREF="https://learning-python.com/mergeall.html">site_</A>.

I initially wrote this because I was tired of waiting for 
exhaustive PC-to-flashdrive copies to finish.  It syncs content
quickly by doing incremental propagations using timestamps: only 
changed items are ever updated.  It eventually grew to accommodate
a host of interoperability issues and multiple use cases, and work
on Windows, macOS, Linux, and Android, in both command-line and 
GUI modes (see _<A HREF="2019%20PyAndroid%202.jpg.html">2019_</A> 
for the Android GUI).  

Plus, it's open-source transparent, free to use and mod, and will 
never root through your stuff without your permission—intangibles 
that sharply differentiate it from most cloud-storage options.  
This stuff matters today.

_<HR>
_<I>2023 update_</I>: also watch for the Android+PCs standalone app 
_<A HREF="2023%20Sync%20App.jpg.html">ahead_</A>; it's Mergeall 
with a Kivy GUI face-lift to work around USB and shared-storage
constraints in later Androids.