Regex Tester

RegexPal is a web-based regular expression tester from Dan's Tools. It enables users to learn, build, and test regular expressions with results that update in real time as they type. The tool supports both Javascript and PCRE engines and is accessed through modern web browsers.

Users enter a regular expression and a test string, with matches highlighted immediately. Rolling over a match or part of the expression provides additional details. The interface includes a substitution expression field for testing replacements. A cheat sheet lists syntax for character classes, anchors, escaped characters, groups and lookarounds, and quantifiers with alternation. Available flags include ignore case, global, multiline, extended, extra, single line, unicode, ungreedy, anchored, and duplicate subpattern names.

Expressions can be saved with a name and description for later use or sharing via URL. A library section offers examples and community-submitted patterns that users can search and rate. Undo and redo functionality is available through standard keyboard shortcuts. The site also hosts a collection of top regular expressions such as URL checkers, date format validators, and phone number matchers.

RegexPal forms part of a larger suite of web development utilities offered by Dan's Tools. It is not optimized for mobile devices. Registration provides access to discussion forums and premium features while the core testing functionality remains available without an account.