Can I book a large group of passengers on the same flight through your flight booking API, or do I have to do that offline with the airline?

Partly yes, but there is a limit. Airlines and the systems sitting behind the API only allow a small number of passengers in a single booking, and once your party is bigger than that, the airline treats it as a group and handles it through its own group desk rather than through a normal booking request. So small families and small parties are no problem at all, while a coach load of pilgrims or a wedding party is a different process.

When the party is only slightly over the limit, the usual workaround is to split it into two or more separate bookings on the same flights. This does work, but you should know what you are accepting. Each booking gets its own reference and is priced on its own, so if the cheaper seats run out part way through, the second booking can come back dearer than the first. You also ticket and pay for each one separately, and the airline does not guarantee that the two bookings will be seated together.

For a genuine group, the airline group desk is still the right route in most markets. Group fares, longer time to pay and held seats are things the airlines keep for their group teams, and they are generally not offered through a live booking connection. Whether any of your connected suppliers allow group requests to be raised electronically depends on that supplier and on your plan, so it is not something we can promise across the board.

If group work is a regular part of your business, tell us the sizes you deal with and we will confirm what each of your connected suppliers permits, and you can try a booking at the maximum passenger count in the test environment before you quote a customer.