To check-in online with Republic Airlines, go to the airline's website and click on the "Check-In" button. You will then be prompted to enter your confirmation number and last name. Once you have entered this information, you will be able to select your seat, print your boarding pass, and check any baggage. Online check-in typically opens 24 hours prior to the scheduled departure time of your flight and closes 45 minutes before departure for domestic flights and 60 minutes before departure for international flights. It's always a good idea to double check with the airline for exact check-in times and procedures.