There are apps to check the weather, rail timetables and your bank balance.
Now they can help you check if your partner is cheating on you.
A number of apps have been created that allow those of a jealous disposition to track their partner using GPS.
For the more controlling, they can also intercept and read communication made by their significant other - including texts, social media messages and phone calls, though both partners need the app on their phone.
Figures reveal more than 40 per cent of people in Britain have admitted to checking their partner's phone - a quarter having done so without consent.
MCouple, developed by US surveillance firm mSpy, offers a GPS tracker, contacts viewing, Facebook message reader and SMS and phone tracker.
Couple Tracker, the 79p app which has had up to five million downloads, sells itself as "the best affair and cheating prevention and detection mobile application".
Its features include GPS-tracking every half hour, full call history and a statistical overview of everyone commenting and liking their partner's Facebook posts.
Relate counsellor Christine Northam said if both sides want it, the app can be beneficial.
"If, on the other hand, it is a 'need' in a relationship, someone thinking 'I must know where exactly my partner is', then I would question why."
- Daily Mail