Hi there, among the At Denver International Airport (DEN) Frontier Airlines DEN Terminal operates out of Terminal East. Being an ultra-low-cost carrier, it offers budget-friendly fares but extra charges for baggage, seat selection, and other services. Although mobile check-in and kiosks are helpful, lines can still be lengthy; Thus, arriving early is advisable. Especially during peak hours, wait times for security may differ. For those who are ready for a basic experience, it serves as a reasonable choice for travelers on a budget.