Can a flight booking API handle a trip where my customer visits several cities before flying home?

Yes, most flight booking APIs can handle multi city trips, where a customer flies from one city to another, then on to a third, and home from there. Your search form needs to allow more than two rows of travel so each leg can be entered with its own date, and the results come back as one itinerary priced together rather than as separate tickets.

There are limits worth knowing about. Airlines and suppliers usually cap how many legs a single booking can hold, and some content sources only support simple return and one way searches, so the multi city option may be missing or may bring back far fewer results. Fares for these trips are built from special rules, so a route that looks perfectly sensible to you can come back empty simply because no airline offers a through fare for that combination of cities.

When a genuine multi city fare is not available, the usual answer is to sell the trip as separate tickets, one for each leg. That works, but your staff and your customer should both understand that separate tickets are treated separately by the airlines. A delay on the first leg does not protect the next one, and any change or refund applies to one ticket at a time rather than to the whole journey.

Before you advertise this kind of trip, run a few real searches on the routes your customers ask for most and check that your supplier returns priced results for them, then decide how your portal should offer separate tickets when it does not.