Hack

https://pentesterlab.com/

https://app.hackthebox.eu/dashboard

https://academy.hackthebox.eu/dashboard

https://www.hackthissite.org/

https://www.hacksplaining.com/

https://www.hacking-lab.com/index.html

https://cryptopals.com/

https://ocw.cs.pub.ro/courses/cns

https://www.pentesteracademy.com/

https://tryhackme.com/

https://learn.hacktify.in/collections?category=courses&page=1

https://crackmes.one/