I use the app PeakFinder all the time and it’s incredible for determining what mountain is what when you’re on the go!
I used to use PeakFinder, but then it was withdrawn and the free version disabled. Now it costs $5.
This is a well polished app, which has non-trivial technical solutions (the AR view works very well and must not have been so simple to implement reliability on a miriad of different android devices).
5 dollars! C'mon.