API (Advance Passenger Information) data is biographic information on passengers (as contained in travel documents) collected by air carriers during check-in and, complemented with travel route information, transmitted by these carriers to the border control authorities of the country of destination.

API stands for Advance Passenger Information. It is a mandatory requirement by many governments (including the U.S., UK, and EU) that airlines collect and transmit specific passenger data to border control authorities before the flight departs. On your boarding pass, "API" or "APIS" usually indicates that this data has been successfully collected and verified. The information includes your full name, date of birth, gender, nationality, and travel document details (passport or ID number). In 2026, with the full rollout of systems like the EU’s Entry/Exit System (EES), providing accurate API is more critical than ever; if this information is missing or incorrect, you may be unable to check in online or be denied boarding at the gate. Some airlines also use "API" to refer to their internal "Application Programming Interface" in technical contexts, but on a travel document, it almost always refers to the security manifest shared with customs and immigration to screen for security risks before you even land.