Yes, Ryanair strictly requires Advance Passenger Information (API) for almost all international flights. This information is a legal requirement mandated by government authorities for security and border control. Passengers must provide their passport or national ID card details, including the document number, expiry date, and nationality, during the online check-in process. In 2026, Ryanair’s systems are highly integrated with this data; if you fail to provide your API before arriving at the airport, you will likely be unable to download your boarding pass and may be forced to pay a heavy "Airport Check-in Fee," which can be as high as £55 or €55. For flights to or from the UK, the EU, and Morocco, this data is transmitted to border agencies before takeoff. It is essential to ensure the API matches your travel document exactly, as discrepancies can lead to being denied boarding at the gate. You can manage and save your API within the Ryanair app's "MyRyanair" profile to make future bookings and check-ins faster and more accurate.