https://www.hackthebox.eu/ - Pentest Lab (free + paid subscriptions)

https://www.vulnhub.com/ - Vulnerable offline VM challenges (lots of great content here)

https://exploit-exercises.com/ - Vulnerable offline VM challenges

https://w3challs.com/ - Online challenges in multiple categories

http://smashthestack.org/wargames.html - Online challenges

https://www.hackthissite.org/ - Online challenges in multiple categories

https://hack.me/ - Similar to vulnhub

https://www.root-me.org/ - Online challenges & virtual environments

https://www.enigmagroup.org/ - OWASP top 10 based challenges

https://www.hackthis.co.uk/levels/ Over 50 challenges with multiple categories

http://www.kioptrix.com/blog/test-page/ - Offline VM challenges

http://bright-shadows.net/ Over 300 challenges with multiple categories

https://microcorruption.com/login - Embedded Security CTF

http://www.dvwa.co.uk/ - Damn Vulnerable Web App (DVWA)

https://www.owasp.org/index.php/Category:OWASP_WebGoat_Project - Web Goat (OWASP)

https://sourceforge.net/projects/metasploitable/ - Metasploitable

https://overthewire.org/wargames/ - Step-by-Step Pentest Lab

https://www.hacking-lab.com/ - Pentest Lab (free + paid subscriptions)

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