neat site! clicking an example opens up a playground with live update and explanation and railroad diagrams, similar to sites like regex101[1] and regulex[2]

one suggestion would be to mention clearly which tool/language is being used, regex has no unified standard.. based on "Cheatsheet adapted" message at the bottom, I think it is for JavaScript. I wrote a book on js regexp last year, and I have post for cheatsheet too [3]

[1] https://regex101.com/

[2] https://jex.im/regulex

[3] https://learnbyexample.github.io/cheatsheet/javascript/javas...