Compound term (noun): trip planner, journey planner.
Reittiopas often refers to an online application or program which provides routes or timetables for transportation. For example reittiopas.fi is the travel planning website for trams, busses and the metro in Helsinki.
Opas (”guide”) can mean either a book or a person as well as a website or other informational material. The related verb is opastaa, which means ”to guide,” ”to help,” ”to mentor” or ”to lead.”