Check-in settings

Check-in is how you confirm who will actually play before the draw. Turn it on to avoid empty slots in your bracket. Players do it themselves; see Check-in for their side.

Turn it on

In the tournament's Settings tab, under Schedule:

1. Switch on Require check-in.
2. Set Check-in opens and Check-in closes. It must close after it opens. Both are optional: without an opening time, check-in is open straight away, and without a closing time it never closes on its own, so whoever has checked in when you start the first stage plays.
3. Optionally switch on Also close check-in the moment the tournament starts.

You can change all of this until the tournament starts, even after publishing.

The two closes

Check-in closes at Check-in closes. With Also close check-in the moment the tournament starts on, it closes at the earlier of that time and the tournament start.

What check-in does

When it is on, it does three things.

1. Enforces the window. Players can check in only while it is open. With the switch off, check-in still works but no window applies.
2. Decides who is seated in the first stage. Before the stage starts, the stage's participant list shows anyone not checked in marked Not checked in. When you start the first stage, those seats are removed and the remaining seeds are renumbered so the bracket has no gaps. In a first-stage elimination bracket, which you place by hand, the bracket only has slots for those who checked in. A paid seat is refunded. Only the first stage looks at check-in. Later stages never do.
3. Sends notifications. A "Check-in is open" notice goes out once, when the window opens (or right away if you switch check-in on while it is already open). Everyone who failed to check in is told when the stage starts.

Missing check-in is not a forfeit

Participants who miss it are dropped before the draw. They have no matches and no forfeits, and you do not need to remove them yourself.

Check people in by hand

On the Participants tab, flip the Check-in switch on a row, or select several and use Check in or Check out. This ignores the window. It is locked once a stage has started, because the first stage has already seated whoever was checked in. Players can only check themselves in once their entry is approved.

Related

Registration and Stages and seeding.