fzy - A better fuzzy finder
DocFetcher - DocFetcher is a portable German/English open source desktop search application.
skim (fuzzy finder) - Discover open source libraries, modules and frameworks you can use in your code
SearchMyFiles - Alternative to the standard Search For Files And Folders module of Windows. Duplicates search is also supported.
Everything by Voidtools - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
Recoll - Recoll is a desktop full-text search tool. Recoll finds keywords inside documents as well as file names.