I have a huge collection of PDF. Mostly it consists of research papers, of self-created documents but also of scanned documents.

Right now I drop them all in one folder and give them precise names with tags in the filename.

But even that gets impractical, so I am looking for a PDF library management application. I am thinking of something like Yep for Mac, with the following features:

• PDF cover browsing (with large preview, larger than Nautilus allows)
• tagging of PDF (data should be readable cross-platform)
• possibility to share across network (thus rather flat files than database)
• if possible: cross-platform

Mendeley seemed to be a good choice, but I am not only having academic papers and don't want to fill it all metadata that is required there.

The only alternative I could find thus far is Shoka, but the features are limited and developments seems to have stopped already.