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.
allTags - allTags is a free, tag based file management application.
Szurubooru - Image board engine, Danbooru-style. Contribute to rr-/szurubooru development by creating an account on GitHub.
Elyse - The free version allows up to 30 tags.
Konachan - Imageboard dedicated to anime, manga, and Japanese games wallpapers / backgrounds.