Several GPS based Apps are available which some orienteering clubs set courses on. They are a way to set training without needing to put out control makers. They rely on mobile phone GPS signal which is OK in urban races and parks, but may struggle under tree cover.

MapRun

http://maprunners.weebly.com/

MOBO

http://mobo.osport.ee/help?lang=en

Usynlig-O

https://usynligo.no/about

iorienteering

http://www.iorienteering.com/

GPS Orienteering

http://www.hippsomapp.se/?lang=en

Other useful Apps

What 3 words

This App divides the world into 3 x 3 metres squares and assigns three words as the unique identifiers to each square.

https://what3words.com/daring.lion.race

IOF list of orienteering software

This list includes the full range of software relevant to orienteering.

https://orienteering.sport/iof/it/list-of-software-for-orienteering/