The Spirit Airlines flight check-in process is quick and budget-friendly if done online. You can check in starting 24 hours before your scheduled departure through the Spirit Airlines website or mobile app. This allows you to choose your seat, add bags, and get your boarding pass—either printed or mobile. Checking in at the airport is available but may include extra fees. For domestic flights, you must check in at least 1 hour before departure; for international flights, allow at least 2 hours. To avoid delays and additional costs, use online check-in for a smooth travel experience with Spirit Airlines.