regexxer is described as 'nifty GUI search/replace tool featuring Perl-style regular expressions. If you need project-wide substitution and you’re tired of hacking sed command lines together, then you should definitely give it a try' and is an app in the Development category. There are more than 25 alternatives to regexxer for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and BSD. The best alternative is grepWin, which is both free and Open Source. Other great apps like regexxer are grep (Free, Open Source), dnGREP (Free, Open Source), Search Monkey (Free, Open Source) and AstroGrep (Free, Open Source).
grepWin is a simple search and replace tool which can use PCRE regular expressions to search for strings of text within files. grepWin adds an entry to the shell context menu to easily search selected folders.
AstroGrep is A Microsoft Windows GUI File Searching (grep) utility. Features include regular expressions, versatile printing options, stores most recent used paths and has a "context" feature which is very nice for looking at source code.
Quickly search through large numbers of files on your PC or network using powerful text patterns to find exactly the information you want. Search and replace with plain text or regular expressions to maintain web sites, source code, reports, ...
Search and Replace for Windows is a fast, easy to use grep utility for search and replace in multiple files, directories and archives. Supports grep style Regular Expressions. Script language for webmasters and programmers.