I use Calibre to organize papers. About 3/4 the time it can successfully extract the title and authors - I manually correct the mistakes it makes, fill in the g

I use Calibre to organize papers. About 3/4 the time it can successfully extract the title and authors - I manually correct the mistakes it makes, fill in the gaps and tag them. The software then organizes them in directories based on this information in a user-defined way. It's not perfect. In particular it's missing tag hierarchies which would make it more intuitive to navigate to things without giving each paper dozens of tags and such.