(Originally) a person who plans a route or routes, especially as a job; (now also) a software package, website, etc., designed to assist a person in planning a route or routes.
Origin
Early 20th century.
Definition of route planner in US English:
route planner
noun
(Originally) a person who plans a route or routes, especially as a job; (now also) a software package, website, etc., designed to assist a person in planning a route or routes.