Jettova
7.9#4 in travel itinerary appsFrom $34.99 a yearFree planAndroidiOSWebAPI
VisitJettova suits solo travelers and groups who want to build itineraries, coordinate dates and preferences, and split trip expenses. Developers may also find its API useful for meeting-city rankings and other listed travel tools.
You want what its maker publishes above — check its page for the details.