Hacking Challenges

https://ctf.hackerfire.com

http://www.janosgyerik.com/hacking-contest-on-a-live-cd/

https://contained.af/

https://smashthestack.org

https://www.pentestpractice.com/challenges

https://ctf.saluslab.net/

https://demo.ctfd.io/

https://potatopla.net/crypto/

https://cryptopals.com/

https://ctf.hak4kidz.com/

https://www.holidayhackchallenge.com/

https://github.com/Hackademic/hackademic/

https://www.amanhardikar.com/mindmaps/Practice.html

https://www.brainquest.sk/

https://www.bright-shadows.net/

https://www.canyoucrackit.co.uk/

https://www.canyouhack.it/

https://www.captf.com/practice-ctf/

https://www.chall.stypr.com/

https://www.chall.tasteless.eu/

https://www.challengeland.co/

https://www.cmdchallenge.com/

https://www.codechef.com/contests/

https://www.counterhack.net/Counter_Hack/Challenges.html

https://www.cryptoclub.org/challenges/index.php

https://www.ctf.forgottensec.com/wiki/index.php

https://www.dareyourmind.net/

https://www.dftt.sourceforge.net/

https://www.en.hacktest.net/

https://www.enigmagroup.org/

https://www.exploit.co.il/projects/vuln

https://www.exploit-exercises.com

https://www.gendou.com/crypto/

https://hack.me/

https://www.hackburger.ee/

https://www.hackergateway.com/

https://www.hacking-challenges.de/

https://www.hacksplaining.com/exercises

https://www.hackthebox.eu/

https://www.hackthis.co.uk/

https://www.hackthissite.org/

https://www.halls-of-valhalla.org/beta/challenges

https://www.hellboundhackers.org/

https://www.ismellpackets.com/category/packet-challenge/

https://www.javaist.com/rosecode/problems.php

https://lab.pentestit.ru/

https://www.lost-chall.org/

https://www.me.hack.me/login

https://www.microcontest.com/

https://microcorruption.com/login

https://www.mod-x.co.uk/

https://www.netforce.nl/challenges/

https://www.netresec.com/

https://www.newbiecontest.org/index.php

https://www.noe.systems/

https://www.overthewire.org/wargames/

https://www.p0wnlabs.com/free/forensics

https://www.pentest.training/index.php

https://www.pentesterlab.com/exercises/

https://www.plaidctf.com/

https://www.practicalpentestlabs.com/

https://www.praetorian.com/challenges/pwnable

https://www.pwnable.kr/index.php

https://www.pwnable.tw/

http://pwnadventure.com/

https://www.questionengine.securitytreasurehunt.com/

https://www.rankk.org/

https://www.reversing.be/

https://www.reversing.kr/

https://www.root-me.org/lang=en

https://www.ringzer0team.com

https://www.sabrefilms.co.uk/revolutionelite/

https://www.slavehack.com/

https://www.solveme.peng.kr/

https://www.spoj.com/problems/classical/

https://www.suninatas.com/

https://www.tdhack.com/

https://www.thisislegal.com

http://www.trythis0ne.com/index.php

https://www.trytodecrypt.com/

https://www.vulnhub.com

https://www.w3challs.com/

https://www.wargame.kr/challenge

https://www.wixxerd.com

/https://www.yashira.org/

https://www.yoire.com/