Read more: What is CTF.

No, but you can get a lot of CTF-related information.

Send membership request using form in your Profile:

If your team has active members, they will need to approve your request or send you an invitation code:

Invitation code can be found in Profile -> Your teams -> Edit your team

If your team has no registered members, administrators will approve your membership request, and then you will be able to manage your team yourself.

You can mark your team as "Academic" if your team is comprised of university students or academics only and associated with some university.

Well, you can play alone or try to get a team. It's more fun to compete with a team. You can hire people from your university or your job. Don't forget to provide your skills in Profile page and check "I'm looking for the team" - may be someone will invite you. Also, you can try to use our talent search interface.

use Aliases in Profile -> Your teams -> Edit your team

If you want to change team name you can create a new team, join both then merge them.

We don't recommend changing team names but keep mulitple teams if they're from different periods of time or their names are not similar to each other.

Two team members can remove any other team member. The only limitation is they should join a team earlier than 15 days ago. If there are only 2 members in a team, then one member can remove the other. Also, team member can leave a team by himself, so you can politely ask your member to leave.

So, be careful accepting team membership requests or sharing membership keys. Use feedback form to contact us in special case.

Read more: Rating formula

Also, CTF organizers get rating points for their events.

Weight is a parameter used in rating formula to count team ratings. Weight is determined from team votes or set by CTFtime admins. In 2017 rating events previous years weight used if available or determined via voting overwise.

For some events public weight voting is open from the begining of CTF event and a week after (or by the end of the current year if it happens). Team members of last years top 50 and teams scored > 0 points can vote. 2021 change: only teams who participated at least in two events can vote. The vote counts on behalf of your team. Important change: starting from 2021 only team players who joined team before the event can vote. When multiple teammates vote, we take the average. If you change your mind, you can re-vote, but only once. Your first vote is discarded then. For the first time events and events having weight less than 25 weight vote limit is 25*. For the others is last years weight multiplied by X. X = 2 for attack-defence events and 1.5 for the rest. Event organizers and winning team can't vote. N.B. We don't like cheaters or spammers. *If there are more than one event during the first year - all of them will get maximum weight of 25.

Yes, check the API page.

You can use our API to export data in JSON format.

All merges are manual - you need to send merge request via special form.

Notice:
if you played with some team for a couple of years and now want to play with another team, be polite - don't loose history merging those teams, just create a new one. If you going to merge teams after some CTF - don't do it, just add an alias to your team before the event.

You can't merge teams ever participted in the same contest.

You need to join the team, then go to "Events tasks" and click at "+" to the right of the task you want to post a writeup on.

If there is no tasks added for your event - please ask your organizer to add them or add them yourself.

We noticed that most CTF teams websites do not live long. That mean - all their writeups are gone after some time. We ask you to post a copy of your writeup to CTFtime, so new generations of CTFers can use them for study.

Yes, you can delete it here.

No you can not.

Well, sometimes we give them away at the conferences, but you always can print it yourself.