Ryanair's online check-in window is famously strict and varies based on whether you have paid for a seat assignment. If you have purchased a reserved seat, you can check in as early as 60 days before your scheduled departure. This is a significant benefit for travelers who want to handle their documentation well in advance of their trip. However, if you choose the "random seat allocation" (which is free), the check-in window is much smaller, opening only 24 hours before the flight and closing strictly 2 hours before departure. It is critical to complete this process via the Ryanair app or website, as failing to check in online will result in a "Boarding Pass Issuance Fee" at the airport, which can be as high as €55/£55 per person. For most passengers, the digital boarding pass on the app is sufficient, but some non-EU/EEA citizens may still be required to print a paper pass for a manual "Visa Check" at the airport desk. Always aim to check in as soon as the 24-hour window opens to ensure you don't run into technical issues or forget as the departure time approaches.