TagSpaces - TagSpaces is an open source platform for personal data management. With TagSpaces you can manage and organize the files on your laptop, tablet or smart phone.

Danbooru - Danbooru is an advanced, tag-based image board system that is based on Ruby On Rails.

Tabbles - Tabbles use tags to organize and find files along with your colleagues.

Hydrus - A personal booru-style media tagger that can import files and tags from your hard drive and popular...

allTags - allTags is a free, tag based file management application.

TAGXFS - Tagxfs is a semantic file system. It extends the user space file system to a tag based hierarchy.