CTFtime
The de facto calendar and ranking system for the global Capture the Flag scene, listing upcoming and past competitions, rating teams on performance since 2011, and archiving write-ups from finished events. Useful once you have done a beginner CTF like picoCTF and want to find the next one to join.
Community
Other
CTFtime team
Ongoing
Intermediate
Free
What it is
CTFtime is a community run hub for competitive Capture the Flag events. Its calendar lists CTFs happening worldwide with dates, format (jeopardy or attack-defence, online or on-site), and organiser, so it functions as the place people check to find out what is running this weekend. Alongside the calendar it maintains a team rating system going back to 2011, calculated from results across the year's rated events, and an archive of write-ups that teams publish explaining how they solved specific challenges after a competition ends.
Why it is worth the time
Once someone has tried a beginner focused event like picoCTF, the natural next question is where to find more competitions, and at what level. CTFtime answers both: the calendar surfaces events by date and category, and the ratings give a rough sense of how competitive a given CTF tends to be, which helps someone new decide whether to jump into a highly rated international event or start with a smaller, more forgiving one. The write-up archive is also one of the best free sources of worked security problems available anywhere, since it captures real reasoning from real competitions rather than sanitised textbook examples.
Free versus paid
Entirely free, with no account required to browse the calendar or ratings, and a free account only needed to register a team.
Who it suits
Anyone who has already done at least one structured CTF or wargame (picoCTF, a TryHackMe room, or similar) and wants to keep practising competitively, plus anyone curious about which teams and organisers are active in a particular country or category, such as web exploitation or reverse engineering.
Ethics and scope
CTFtime itself hosts no challenges; it indexes events run by other organisers, each of which sets its own rules and infrastructure for legitimate, sanctioned competition. The general rule still applies: skills practised in a CTF are for that CTF's infrastructure. Only test systems you own or are explicitly authorised to test: your own lab, a CTF, or an in-scope bug bounty programme. A CTF's rules usually forbid attacking the scoring infrastructure or other teams, so read them before you play.
Common questions
Do I need a team to use it? No, browsing the calendar and write-ups needs no account, though registering to compete usually means forming or joining a team. Is it only for advanced players? No, the calendar includes beginner friendly events, and the write-up archive is a learning resource in its own right regardless of whether you compete. How current is it? Organisers submit their own events, so coverage is broad but not perfectly exhaustive; well known CTFs are reliably listed.
Ready to start?
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Stuck on something specific?
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