Great work; do you have a blog post discussing the implementation?

It would be even cooler, and much faster, if all the work could be done client-side. e.g. similar to debuggex.com

If you select JavaScript as the regex implementation it seems to do the work client-side.

Unlucky I'm not the author of the tool... :)

as a server-side regex parser, how do you handle catastrophic backtracking?

http://www.regular-expressions.info/catastrophic.html

this seems to handle /(x+x+)+y/ and 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' gracefully - this should take exponential time (in the number of 'x's) to resolve.

edit: seems you don't ... PHP (PCRE) is fine (php handles this well?), javascript is presumably just using my own CPU, but selecting Python allows me to use arbitrary server CPU ... sorry about that ;)

edit2: HN comments tend to focus on the negative ... pathological input handling aside, I really like it.

Hello

I'm the creator. PCRE offers a neat feature to limit backtracking, Python does not. I still havent found a decent solution to this issue.

Javascript is run in your own browser so you'll only be screwing yourself there :p

Looks just like http://rubular.com/ to me but I guess it covers some different languages

Great tool - just wish there was an offline version I could run!

shameless plug for my own free regex tool: www.regexpixie.com

Windows only?