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By default, guests can register for a Cal Event from the moment you publish it until the event starts. Set a registration window to open registration later, for example at a set launch time, or to close it before the event starts so you can lock the guest list.
The Settings tab under Attendance in the Cal Event editor, with the Registration window section showing a Registration opens time and a Registration closes time

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Set the registration window

1

Open the event's settings

Go to Events, open the event, and select Attendance → Settings.
2

Choose when registration opens

Under Registration window, pick a date and time for Registration opens. Leave it empty (it reads When published) to open registration as soon as the event is published.
3

Choose when registration closes

Pick a date and time for Registration closes. Leave it empty (it reads When the event starts) to keep registration open until the event starts.
4

Save

Save the event. The preview next to the editor shows what guests see right now.
Times are set in the event’s time zone, and the pickers don’t offer anything after the event starts. To go back to the default for either time, clear it with the clear button next to the picker.

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Rules for the window

Cal.com checks the window when you save: The message appears under the picker that needs changing. If you save from another tab, the editor opens Attendance → Settings so you can fix it. The same rules apply when you move the event’s start time: a new start time earlier than the registration close time can’t be saved. If you change the event’s time zone, the registration times keep the same date and time on the clock in the new time zone.

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Who can change the window

These people can set and clear the registration window:
  • The event’s hosts
  • Team members whose role lets them edit the team’s events
  • The owner of a personal event
Co-hosts see both pickers turned off with Contact the main host to change this setting. They can still save their other changes to the event, and their saves leave the window as it is.
Duplicating an event doesn’t copy its registration window. Set it again on the new event.

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What guests see

The event page, the embed and the editor preview show guests where the event is in its registration window. The page updates when registration opens or closes, without a reload.
A Cal Event's public page where the Registration panel shows Registration not open yet and the date and time registration opens
Dates and times on the event page are shown in the guest’s time zone, with the time zone’s short name.
A Cal Event's public page with the Join waitlist button and the date and time registration closes shown underneath
Guests who are already registered, on the waitlist or waiting for approval keep seeing their own registration status instead of the window. A cancelled or ended event shows that state instead.

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Notify me

Before registration opens, guests can select Notify me on the event page or the embed and leave their email. Signed-in guests subscribe their account’s email in one tap. Cal.com sends each of them one email when registration opens, with a link to the event page. If you move the open time later, or clear it, the email follows the new time. Guests aren’t emailed if you cancel the event or registration closes before they’re told. Every email has an unsubscribe link, and the list of addresses is deleted once the event ends.

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How the window is enforced

Cal.com checks the window on its own clock every time someone registers, so a guest can’t register outside the window from an old tab or by texting an RSVP. Joining the waitlist counts as registering and follows the same window. Promoting guests who are already on the waitlist doesn’t. If a seat frees up after registration closes, guests on the waitlist can still be promoted into it, by a host or automatically, until the event starts.

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Set the window with the API

You can also set the window with registrationOpensAt and registrationClosesAt when you create an Event or update an Event with API v2. Send times in ISO 8601 in UTC, or null to use the default. The same rules apply as in the editor.

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Set the window with the assistant

You can also ask the Cal.com assistant when registration opens and closes, or to set or clear either time. It shows the new window on an approval card before saving, and the same rules apply as in the editor.