Scherlokk - Mac OS X application. Simple and user friendly, Scherlokk will find your media and missed files - quickly.
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.
Slingscold - Slingscold is a lightweight application launcher similar to Launchpad in Mac OS X.
TagFlow - TagFlow is an intelligent files manager that use tags for organize your documents.
kupfer - Kupfer is a command tool heavily inspired by https://alternativeto.
Tabbles - Tabbles use tags to organize and find files along with your colleagues.