RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.
SearchMyFiles - Alternative to the standard Search For Files And Folders module of Windows. Duplicates search is also supported.
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.
SMF – Search my Files - SMF - Search my Files v13 is the fastest duplicate files finder and a multi-dimensional - file searcher, - file copier / mover, - file deleter / eraser, - and
regular expressions 101 - Extensive regex tester and debugger with highlighting for PHP, PCRE, Python and JavaScript.
DocFetcher - DocFetcher is a portable German/English open source desktop search application.