General CTF
- Net-Force | Challenges
- https://ctfs.me/
- http://www.wechall.net/challs
- Mod-X Security Challenge
- Welcome [Root Me : Hacking and Information Security learning platform]
- https://picoctf.com/
- http://hax.tor.hu/welcome/
- Home - RingZer0 Online CTF
- https://backdoor.sdslabs.co/
- Shell-Storm repository
- https://w3challs.com/
- https://ctflearn.com/
- https://ctf365.com/
- https://www.hellboundhackers.org/
- https://www.hackthis.co.uk/
- https://www.enigmagroup.org/
- Capture the Flag - Application Security Challenge
- http://bright-shadows.net/
- https://ctf101.org/
- https://hackcenter.com
- https://www.hackthissite.org/
- https://www.rankk.org/
- https://canhack.me/
- Prügivedu
- 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/
- Reversing.Kr
- MalwareTech Labs - Learn Reverse Engineering & Malware Analysis
- https://crackmes.one/
- https://challenges.re/
- Crackmes | Reverse Engineering
- 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
- pwnable.tw
- https://www.pentestpractice.com/
Wargames
- http://io.netgarage.org/
- http://smashthestack.org/wargames.html
- OverTheWire: Wargames
- https://chall.stypr.com/
- http://www.underthewire.tech/wargames.htm
Cryptography
- http://cryptopals.com/
- https://id0-rsa.pub/
- Electrica the Puzzle Challenge
- try to decrypt - your brainteaser
- https://www.cryptoclub.org/challenges/index.php