If you have a computer with internet connection available at the day of the event, you can use your computer to manually check in attendees.
1. Go the Attendees page for the relevant event, and access the Attendees tab.
You will see a list of all the attendees who have tickets for your event.
2. You can search by the name of the attendee, or the ticket ID.
(to search on ticket ID, please add a # before the ID: e.g. "#31" for ticket ID 31)

3. You can check-in the attendee by clicking "Check in".

"The attendee is checked in" confirmation will be displayed on the top of the screen.
4. You can check all checked in attendees by filtering on "Checked In".
In case you want to undo a check-in, you can do so by clicking the "Undo Check in" button.
Note:
Name Search Check-in becomes available 24 hours before the start of the event.
Attendees can be checked in up until 24 hours after the event has finished.
Name Search Check-in becomes available 24 hours before the start of the event.
Attendees can be checked in up until 24 hours after the event has finished.