[sverhagen]

I want to call out https://www.regular-expressions.info/ since it was, for a long time, one of the better/best resources on regexes that I was able to find. I learned a lot from this ... guy, essentially.

[nerdponx]

This website is great and well worth a donation if you've benefited from it in the past.

As a "next level" site, also give https://rexegg.com a look.