TLDR : zpaqfranz = no go
The strongest element of all is right at the beginning, in the doc. A (honest) statement from the developer line 23 makes it easy to say it’s a no go to build any reliable back-up system upon :
“EXPERIMENTAL BUILD: the source is a mess, strongly in development”
I started reading parts of the code about memory management (aligned malloc and free strategies) to find possible leaks. Then about crypto and the extensive use of SHA1 to search for possible data encryption with weak algorithm. But the 100k lines are hard to navigate into and the code is complex (for someone new to it at least).
Another red flag is about some huge commits to add some feature, probably WIPs (ie. Add files via upload · fcorbelli/zpaqfranz@a56f3ed · GitHub and Add files via upload · fcorbelli/zpaqfranz@45ae46c · GitHub)
Finally, there seem to be some dynamic testing / integrity mecanisms but I don’t find static testing framework to check some program specs. I wouldn’t run an untested software of this size to manage my data.
I won’t dig deeper into zpaqfranz code