Under The CTF is a set of software challenges.
More information about Capture The Flag events can be found at Wikipedia.
Proceed to the challenges!
Please do not attack the scoreboard or challenge infrastructure :-)
Everything you need to solve the puzzles is on this site.
Note: the Python challenges all use Python 3.6.
The project source code is available at https://github.com/dwyde/challenges.
Use this if you want to look behind the scenes, or to run the software locally.
If you're looking for something more beginner-friendly,
I also wrote introductory coding exercises called Tricycle.