Debuggex is described as 'Intuitive visual regular expression debugger, tester, and helper' and is an website in the development category. There are more than 25 alternatives to Debuggex, not only websites but also apps for a variety of platforms, including Windows, Mac, Linux and Self-Hosted apps. The best Debuggex alternative is RegExr, which is both free and Open Source. Other great sites and apps similar to Debuggex are regular expressions 101, Expresso, RegexMate and Wildcard.
Debuggex's best feature was the visualiser. I can't find another site that has exactly that, but the RegExr explainer at the bottom of the page is a good alternative. Plus, the interface is clean, the cheatsheet is handy, and the 'Community Patterns' are helpful.
Regex101 is a powerful, online regular expression tool with extensive support for multiple languages including PHP, PCRE, Python and JavaScript.
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 or web designer with an extensive knowledge of regular expressions.
RegexMate offers seamless regex crafting and testing on macOS and iOS. Its minimalist interface provides an instant live preview, and users can save their expressions into a library for quick reference. A comprehensive guide with tutorials is always accessible, with light and dark mode options.
Wildcard gives you a nice and simple to use interface to test/practice regular expressions.
RegexBuddy is your perfect companion for working with regular expressions. Learning, creating, understanding, testing, using and saving regular expressions has never been easier.
Regex Generator is a tool to generate simple regular expressions. The goal is that people with less experience can create regex smoothly.
The only one Regular Expression tester you need, that will help you to test your regular expressions in flavors:
.NET regular expression tester with instantaneous highlighting, code completion, and C# and VB.NET code generation.
An online JavaScript regular expression tester. Enter a regex expression and test data and determine if matches are made.
The Regex Coach is a graphical application for Windows which can be used to experiment with (Perl-compatible) regular expressions interactively. It has the following features:
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It seems that Debuggex will be unavailable after November 30th. This shows on login attempt on debuggex.com.