GPS and other mobile technologies

GPS

Android

Viewranger
https://play.google.com/store/apps/details?id=com.augmentra.viewranger.android

GPS logger
https://play.google.com/store/apps/details?id=com.mendhak.gpslogger

Apple

Viewranger
https://itunes.apple.com/gb/app/viewranger-outdoors-gps-open/id404581674?mt=8

GPS X Motion
https://itunes.apple.com/us/app/motionx-gps/id299949744?mt=8

Geocaching

Android

C:geo
https://play.google.com/store/apps/details?id=cgeo.geocaching&feature=search_result#?t=W251bGwsMSwxLDEsImNnZW8uZ2VvY2FjaGluZyJd

Geocaching.com
https://play.google.com/store/apps/details?id=com.groundspeak.geocaching&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5ncm91bmRzcGVhay5nZW9jYWNoaW5nIl0.

Apple

Geocaching.com
https://itunes.apple.com/us/app/geocaching-intro/id329541503?mt=8

QR Codes

Android

QR Code reader
https://play.google.com/store/apps/details?id=la.droid.qr

Apple

QR code reader
https://itunes.apple.com/gb/app/qr-reader-for-iphone/id368494609?mt=8