Update to RegExr: Learn and Test RegEx Online

I just released a new version of RegExr, the free online application for learning and testing regular expressions. This release includes a number of minor bug fixes, and a few big new features.

Real-time expression editing

Matches are now displayed in real-time as you edit your expressions.

Code sense

This build has early support for displaying inline code tips when you mouse over your expression.

Infinite match notification

The expression will now turn red if it will result in infinite matches.


You can now access RegExr at RegExr.com. This simply redirects to its permanent home at gskinner.com/RegExr/.

If you encounter any problems, have a feature request, or want to provide feedback, please leave a comment below.

Known issues:

The group pre-parser doesn’t do a very good job with nested groups. This only affects the group listing in the info field (bottom), not code sense or the groups listing for matches.

Code sense support is very early, and will likely have some quirks. Please let me know of any issues in the comments below.

Grant Skinner

The "g" in gskinner. Also the "skinner".



  1. Nice tool. You could make it even nicer with bigger slightly fonts 🙂

  2. Thanks very much for this tool Grant. I must admit that RegEx is one of the few things I really hate to learn, just because the language is so concise (not human-readable) and there is so much trial and error. I think I’ll have an easier time getting a handle on it now. Good show.


  3. Amazing tool! Thanks.

  4. Awesome work! Thank you very much!

    I have one feature request, but I realize its been a year since you saw this code probably. Anyway, with replace, it doesn’t seem to support \n and \r in able to split at a match. Any chance that could make it’s way into the app?



  5. Great tool, but the real-time expression editing can be quite nasty with big expressions. How about a switch that lets you turn it on and off? It would certainly be helpful to be able to click an Execute type button with big data sets rather than having to wait a few seconds after each key typed.


  6. +1 for the “Execute” Button from Bob.
    Also it would be very nice if you could add utf-8 support (/u) if possible.

    Thanks a lot for this great Tool!

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