Regular expressions will always be somewhat mysterious, even to the most skilled of programmers. There’s no shame in using a regex tester to fine-tune your queries and one of the top online debuggers, Regular Expressions 101, has just been revamped with a slick interface and more functionality.
Regular expressions are evaluated live, so no need to hit a submit button to see the results. Errors are also shown immediately, along with an explanation to help diagnose the problem. A quick-reference box in the bottom-right corner provides fast access to common commands and tokens.
Finally, you can save expressions as short URLs, making them easy to share with others.
The revamp still has a few kinks to iron out; if you discover any, you can post them to the site’s GitHub repository. Note that the repo doesn’t contain any source code — it’s only used for issue tracking.