picoCTF
Carnegie Mellon's free security challenges for learners
picoCTF is Carnegie Mellon University's free capture-the-flag platform. It has now been renamed CyLab Security Academy, run by the same team. You solve security challenges and find a hidden text called a flag to prove you solved each one.
Free · Login needed · Browser · Beginner
About picoCTF
The library has more than 500 challenges, from beginner to advanced, in areas such as cryptography, web exploitation and forensics. It also runs competitions.
It is made with school students and self-learners in mind, so it is a good first step into security. You need a free account, and accounts are for people aged 13 or older. Existing picoCTF logins still work on the new site.
On Breakpoint since 23 Oct 2026.