RegexPlanet vs The Regex Coach

RegexPlanet is a free web service for testing regular expressions during development. It offers separate test pages for engines including Java, Python, Bun, Go, Deno, Erlang, Haskell, MySQL, .NET, Node.js, Perl, PHP, PostgreSQL, Ruby, Rust, Swift, Tcl, XRegExp, and the browser. The Java tester accepts a pattern, replacement, and multiple input strings, with a control for adding more inputs. Options include case-insensitive matching, multiline mode, and Unicode-aware case folding. The home page provides a field for share codes, and the site directs users to Regex Zone for sharing expressions and finding patterns. A status page reports engine status and says each engine runs separately. RegexPlanet warns that malformed expressions may run indefinitely and that some engines or hosts may face denial-of-service attacks. Its privacy policy describes collection of IP addresses, browser data, and form entries; raw logs are stored by Google CloudRun. The service is offered as-is and as-available.

The Regex Coach is a graphical application for experimenting interactively with Perl-compatible regular expressions. It shows whether a pattern matches a target string and updates the interface when changes are made. Users can highlight captured groups or selected parts of a pattern in the target text. The application can attempt a plain-English explanation of a regex, show its parse tree graphically, and step through the matching process. It also simulates Perl split and substitution operations. Written in Common Lisp, it uses CL-PPCRE as its regex engine. The current Windows download is version 0.9.2; the maker says the program has not changed since 2008. Linux is no longer maintained, though an unsupported 0.8.5 release is available and also runs on FreeBSD. There is no Mac version planned. The program is provided as-is without warranty, and the maker says not to expect support for older Windows configurations or the unsupported Linux release. The engine may overflow its stack with relatively long regular expressions. The listed plan is free, with conditions for commercial use and redistribution.