Dont leave home without it!
We used Citymapper on our visit to London. Transit, walking (and Uber or Lyft although we didnt use them.) Directions were spot on and include pointing you to the best entrances and exits from the Underground. Made using the iconic double-decker buses a breeze. I agree with other reviews that there is an it if a learning curve, take a look before you leave home. And yes, you can set a home address, not sure why some couldnt do that.
donjkrause about
Citymapper, v6.8.1