Regex Shuttle vs RegexRegex

Regex Shuttle is a free browser-based tool for testing, explaining, and learning regular expressions. As users type, it highlights matches and displays match details, groups, and indices. Its explainer separates expressions into tokens and gives plain-English descriptions, while a library provides ready-to-use patterns to copy or open in the tester. A cheat sheet covers regex characters, quantifiers, anchors, groups, and flags. The tool can preview find-and-replace results in real time, including capture-group references such as $1 and $2. It uses JavaScript's built-in RegExp engine, so its behavior follows JavaScript regex behavior in browsers and Node.js. The maker says it supports capturing groups, lookahead and lookbehind assertions, named groups, and Unicode patterns. Regex processing occurs locally in the browser; patterns and test strings are not uploaded, collected, or shared with third parties. The maker says it continues working offline after its first load. No signup or email is required, and the interface is available in English and Chinese. The Free plan is free, with no limits or ads.

RegexRegex is a free browser-based tool for building and testing regular expressions. Its checker runs JavaScript patterns in the browser and shows matches, captures, explanations, and errors, with previews for replacement text. A guided builder composes basic JavaScript patterns using controls for character types, quantities, groups, boundaries, and flags. It can test the pattern it creates, but does not cover every syntax feature or convert arbitrary patterns into an equivalent visual layout. Python, PHP, Java, .NET, and Perl engines can be used by explicitly pressing Run, which sends checks to an online execution service. Replacement previews recognize numbered and named captures such as $1 and $. The searchable reference covers 25 syntax and flag items. Users can save up to 50 test cases in the browser, each with input up to 20,000 characters. Share links include the selected pattern, engine, flags, and operation; test and replacement text are omitted unless users opt in. A cached JavaScript checker may work offline, while checks using other engines need the online service.