DocFetcher - DocFetcher is a portable German/English open source desktop search application.
RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.
Everything by Voidtools - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
Expresso - The award-winning Expresso editor is equally suitable as a teaching tool for the beginning user of regular expressions or as a full-featured development environment for the experienced programmer with an extensive knowledge of regular expressions.
Recoll - Recoll is a desktop full-text search tool. Recoll finds keywords inside documents as well as file names.
rubular - A ruby based regular expression editor