Regex Tester
Test regular expressions with live match highlighting.
What this Regex Tester does
This tool lets you write a regular expression, set the standard flags, and immediately see every place it matches inside your test string. As you type either the pattern or the sample text, the results update live: the total match count, a highlighted preview where each match is wrapped in a yellow mark, and a breakdown of any captured groups for every match.
It is built for developers, data wranglers, and anyone learning regex who wants instant feedback instead of guessing. Because it uses the browser's own JavaScript RegExp engine, the syntax and behaviour are exactly what you get in Node.js and front-end JavaScript code, so a pattern that works here will work in your project.
How to use it
Type your expression into the Pattern field. The leading and trailing slashes shown around the field are just visual delimiters, so enter the pattern itself without them. Use the flag checkboxes to toggle g (global, find all matches), i (case-insensitive), m (multiline, so ^ and $ match line boundaries), and s (dotall, so the dot also matches newlines).
Paste or type the text you want to search into the Test String box. The match count and highlighted output appear automatically. If your pattern contains one or more capture groups written with parentheses, a Captured Groups section lists the contents of each group for every match, which is handy for verifying extraction logic before you copy the pattern into your code.
Tips and notes
The tool always evaluates matches with the global flag internally so it can list every match, even when you leave the g checkbox unticked for display purposes. If your pattern is invalid, a red error box shows the exact message from the JavaScript engine, which makes it easy to spot an unbalanced bracket or a bad quantifier.
Remember to escape characters that have special meaning in regex, such as the dot, plus, question mark, and backslash, when you want to match them literally. Group numbering starts at 1 and follows the left-to-right order of the opening parentheses.