ZeroDays is Ireland's largest CTF. Running since 2015, it has grown to be the largest on-site, one-day CTF in the world. In 2025 over 130 teams of four competed with over 500 competitors in total. The event has three categories for Irish colleges, International teams and an Open section for any team to enter. International competitors welcome. Expect a wide range of challenges suitable for all skill levels; plenty of easy challenges for newer players and some very advanced challenges for experienced players. Thousands of euro worth of prizes including gaming consoles, tablets, lab vouchers etc. Prizes for 1st, 2nd and 3rd place in each of our Colleges, International and Open sections, as well as spot prizes throughout the day. This is an on-site event and will not be accessible to remote teams.