Rome2Rio, Google map, Google translator, Singapore MRT, Subway Metro Mexico, Uber, Indrive, Grab, WhatsApp are my go to apps. Any other recommendations?
It keeps me updated in the minute if a flight is delayed, tells me baggage claim #, what gate I'm landing at, etc and it tracks ALL my flights for the year.
For public transport in Europe, I cannot recommend CityMapper enough! It has been a lifesaver every time we are in London and they have several other major cities in the app as well.