Regular Expressions Puzzles

On 2013 the famous MIT hunt gave a Regexp puzzle, which became very popular.
It appeared several similar puzzles, but there are a couple sites with similar contraption :

Give it a try !

• Regex Crossword
• Regexp Golf
  MIT Hunt
• Online
• Linkedin

MIT puzzle:

More interesting sites:

https://regex101.com/r/wO2zI4/1

https://regexcrossword.com/challenges/intermediate/puzzles/1

https://engineering.linkedin.com/puzzle

https://www.cheatography.com/davechild/cheat-sheets/regular-expressions/

http://mariolurig.com/crossword/