allTags was developed to manage large file sets efficiently. Time-consuming actions, like naming files and choosing folders, are replaced by fast tagging operations.
With built-in support functions, allTags avoids inconsistencies and speeds up file description and retrieval. allTags is 100% free to use.
TaggTool - The Personal File Tagging Utility.
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.
Elyse - The free version allows up to 30 tags.
TMSU - TMSU is a tool for tagging your files.
miTaggedMarks - With miTaggedMarks you organise and access your local bookmarks using tags, instead of the usual hierarchical tree structure. With a new way to handle a large number of tags. Works with nearly any browser.
Tabbles - Tabbles use tags to organize and find files along with your colleagues.