Challenge Lab
Challenges I wrote. Each one has a brief, any files you need, and a flag box that checks your answer in your own browser — no signup, nothing sent anywhere.
Why build my own?
Solving a challenge teaches you the attack. Writing one makes you decide what the weakness is, how much to give away, and what the player should walk away knowing — which turns out to be a much harder question, and a better test of whether I actually understood it.