General CTF
- https://www.net-force.nl/challenges/
- https://ctfs.me/
- http://www.wechall.net/challs
- http://www.mod-x.co.uk/main.php
- https://www.root-me.org/?lang=en
- https://picoctf.com/
- http://hax.tor.hu/welcome/
- https://ringzer0team.com/home
- https://backdoor.sdslabs.co/
- http://shell-storm.org/repo/CTF/
- https://w3challs.com/
- https://ctflearn.com/
- https://ctf365.com/
- https://www.hellboundhackers.org/
- https://www.hackthis.co.uk/
- https://www.enigmagroup.org/
- http://ctf.komodosec.com/index.php
- http://bright-shadows.net/
- https://ctf101.org/
- https://hackcenter.com
- https://www.hackthissite.org/
- https://www.rankk.org/
- https://canhack.me/
- https://hackburger.ee/challenge/
- https://www.hackergateway.com/
- https://www.wixxerd.com/challenges/
- https://www.sabrefilms.co.uk/revolutionelite/
- https://www.challengeland.co/#
- https://ctf.hackerfire.com/
- http://ctf.infosecinstitute.com/index.php
Web Exploitation
- https://hack.me/s/
- http://www.gameofhacks.com/
- https://join.eset.com/en/challenges
- http://www.dvwa.co.uk/
- http://google-gruyere.appspot.com/
- http://www.hackertest.net/
- http://solveme.peng.kr/
- http://www.hacking-challenges.de/
- https://redtiger.labs.overthewire.org/
- https://www.hackthebox.eu/
Reverse Engineering
- https://microcorruption.com/
- http://reversing.kr/challenge.php
- https://www.malwaretech.com/beginner-malware-reversing-challenges
- https://crackmes.one/
- https://challenges.re/
- https://reverse.put.as/crackmes/
- https://join.eset.com/en/challenges
- http://flare-on.com/
- https://ropemporium.com/
Pwn
- http://pwnadventure.com/
- https://exploit-exercises.com/
- http://pwnable.kr/play.php
- https://pwnable.tw/challenge/
- https://www.pentestpractice.com/
Wargames
- http://io.netgarage.org/
- http://smashthestack.org/wargames.html
- http://overthewire.org/wargames/
- https://chall.stypr.com/
- http://www.underthewire.tech/wargames.htm
Cryptography
- http://cryptopals.com/
- https://id0-rsa.pub/
- http://www.caesum.com/game/
- https://www.trytodecrypt.com/index.php
- https://www.cryptoclub.org/challenges/index.php