Square’s past CTFs puzzles are all available as Docker images. I believe all the puzzles have published solutions.

Start here: https://squarectf.com/

If you want to submit fixes to the above site ping me or open a PR here: https://github.com/square/squarectf

Check out Portswigger's Web Security Academy: https://portswigger.net/web-security

This is aimed more at companies signing up rather than individuals, but a company called Security Innovation has a product that kind of gamify's (sp?) hacking vulnerable websites: https://www.securityinnovation.com/training/ (the cmd+ctrl training)

They have a couple of fake websites that have a bunch of vulnerabilities of varying difficulty and you get points for exploiting them.

I am not affiliated with them, but saw a demo once and thought it was cool.

HackTheBox is a good resource to improve your pentesting skills