dJulkalendern is a CTF competition hosted by the D (Computer Science) chapter of THS (Tekniska Högskolans Studentkår), Konglig Datasektionen.

One window is released every weekday in December until christmas eve, resulting in about 17 windows.

The windows contain challenges that range from cryptic puzzles to hacking to other computer science related tasks. The calendar also has an intriguing story which unfolds as you solve each window.


Our organisation



Mathias "Food Elevator" Magnusson

Douglas "BiGd0g" Fischer


We have a Discord server for dJulkalendern! Join it to get announcements from the creators and to talk to other participants!
Are you stuck? Read the challenge carefully and try to google EVERYTHING. After that you could always ask someone skilled in META or our Discord or talk to a friend. The judges will not help you but might, if enough people complain, release a hint or two. Everyone will get access to these hints at the same time so it might be worth it to reload the page even if you've been stuck for a while.


Thanks to everyone who made this possible:

  • Mathias "Food Elevator" Magnusson
  • Douglas "BiGd0g" Fischer
  • Emil "EIM64" Gestsson
  • Viktor "Flop 🦆" Fornstad
  • Karl "Kalle" Lindblad
  • Johan "Bulen" Hahlin
  • Fredrik "Scan" Blomqvist
  • Daniel "Hexakon" Hu
  • Erik Olof Ossian "CosSin" Eriksson
  • Erik "Codzilla" Olsson
  • Alexander "Conclube" Lorentzson
  • Elias "bigfart420" Wetterwik
  • Ivar "haer haer haer hae haer [...] haer haer haer" Boqvist
  • Jimmy "Chai the Tea" Tran
  • Jonathan "Conput" Almgren