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Welcome, hackers of all ages.

DEF CON CTF finals 2020 will take place online, for the first time ever!

We launched a playable archive of our past challenges!

Isn’t it wasteful that challenges get lost after each game? In these crazy times we wanted some preservation, and to create a way to play and practice with ease for everyhacker.

We even started providing hints and videos for some of our old challenges. The archive is in beta, and right now it offers challenges from the 2019 and 2020 quals. If this effort is well received we hope to expand it to more of our challenges, provide more hints, and start archiving challenges that were part of the finals.

If you ran a cool CTF and want to give a shot at archiving your challenges:

Who are we?

We are the Order of the Overflow. We are the current host of DEF CON CTF (Quals and Finals). Read about us and our philosophy here or reach us at

Follow @oooverflow on Twitter for updates!


Public Sources


We owe thanks to many people -- some are listed here