Elyse - The free version allows up to 30 tags.
Everything by Voidtools - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
DEVONthink - DEVONtechnologies develops DEVONthink, DEVONagent, and other Mac and iOS apps for document and information management and web research.
Anytxt Desktop Search - Anytxt is Desktop Search Tool with A Powerful Full-Text Search Engine.
Leap - With Leap you find things based on your natural memory of that file.
Exselo Desktop - Outlook and desktop search to help you search and find information from your files, emails and...