# RegExr - Free Online RegEx Testing Tool

> Markdown version of https://brajeshwar.com/2008/regexr-free-online-regex-testing-tool/ — 2008-03-27

Grant Skinner [released](http://www.gskinner.com/blog/archives/2008/03/regexr_free_onl.html) a Utility Tool -- <a href="http://gskinner.com/RegExr/">RegExr</a>, built with Flex 3, and uses ActionScript 3's built in RegExp engine.

RegExr is an online tool for editing and testing Regular Expressions (RegExp / RegEx). It provides a simple interface to enter RegEx expressions, and visualize matches in real-time editable source text. It also provides a handy RegExp snippet sidebar with descriptions and usage examples to make it easier to learn Regular Expressions through trial and error.

> So far this has only taken a day of development, and the main app is only 150 lines of code. Flex 3 makes this kind of app so darn simple to put together.

RegExr is available online and is free. Grant have promised to release a Free Desktop version built with AIR in a day or two. So, the desktop version can be used on Mac, Windows and Linux (in the near future). The online version requires Flash Player 9.