Page with general CTF/PenTesting guides, tips and tricks
Awesome list with pentest links, tips, cheatsheets
https://github.com/coreb1t/awesome-pentest-cheat-sheets
PortSwigger Web Security Labs - A MUST for web penetration testing!
All labs | Web Security Academy
Stanford - CS 253 Web Security
https://web.stanford.edu/class/cs253/
https://www.youtube.com/playlist?list=PL1y1iaEtjSYiiSGVlL1cHsXN_kvJOOhu-