Hole 19 App | Golf Monthly

I have the Golfshot app on my phone, useful for playing on new courses but I never use it when playing my own course as I know where all the hazards are.

Answer to the original posters question about is it legal, well the software is but the hardware isn't.

see following, taken from RANDA:

it is important that the device only measures distance. The use of a distance-measuring device that is designed to gauge or measure other conditions that might affect a player’s play, such as gradient or wind speed, is not permitted, regardless of whether such an additional function is used or not, and even if that function is disabled.