Great demo, but not very useful in actual practice

Will not accept a regular expression that is more than about 500 characters long.

Doesn’t show capturing groups, except in the output of replacements.

Bought it a while ago, have tried to use it dozens of times, but those limitations made me give up in all but two cases, but those were just when I was demoing something to someone else.

plambert about Patterns - The Regex App