One search per route and date. A one-way route is {"origin": "JFK", "destination": "LAX", "date": "2026-10-20"} or the short form "JFK-LAX-2026-10-20". For a return, add "returnDate", or write "JFK-LAX-2026-10-20-2026-10-27". For a multi-city trip, put two or three legs in order under "legs", each with its own origin, destination and date. Add "lastDate" to a one-way or return route to search every departure day from "date" to it, 7 days at most: each day is a search of its own, so four days means four lists of itineraries to pay for, and on a return the return date moves along with it. Use airport codes such as LHR or JFK, or a city code such as LON, NYC or PAR for every airport in that city. With no date, a one-way route searches the day 30 days after the run. Up to 50 searches a run. They wait together, so five take about as long as one.