Grab is a popular app used in most Southeast Asian countries. It is ideal for you if you are planning to travel solo. Along with being a ride-hailing app, Grab also has a food delivery service, and cashless payment solution.
True to its name, the city mapper app shows you an updated map of the various transport options in Istanbul. The app shows you updated fares, routes, and Metro, bus, trams, and ferry routes. It can also calculate taxi fares and show you cycling routes.