I've only got 6 levels completed, they're targeted at beginners, so if you're experienced with Java Reverse Engineering please wait until I add more levels (Or help me add more levels).
Example launch command: java -cp crackme.jar the.bytecode.club.crackme.level1.Main passw0rd
Beta 1.0: http://the.bytecode.club/crackmes_b1.0.jar (6 levels)
Beta 2.0: http://the.bytecode.club/crackmes_b2.0.jar (7 levels + obfuscation)
Example launch command: java -cp crackme.jar the.bytecode.club.crackme.level1.Main passw0rd
Beta 1.0: http://the.bytecode.club/crackmes_b1.0.jar (6 levels)
Beta 2.0: http://the.bytecode.club/crackmes_b2.0.jar (7 levels + obfuscation)