The Get Taxi app has been available on iOS and Android for quite a long time now, and can be used to hail a black cab to your location and pay for it via the application.
When you first start-up the app and have signed up, Get Taxi will find your location and let you now how far away you are from a cab, via the radar functionality you can see how many cabs are around your current location and see full driver information including their number plate, phone number and picture.
You can also pre-book a taxi for a later date, telling the application where you want picking up and when, once the taxi is on route the application will tell you exactly how far away the taxi is from reaching your destination.
Once the journey is finished you can then pay for the taxi via cash or card.
However this application will only work in the London area, so anywhere else and you will defiantly struggle to find a taxi using it, but you do get rewarded points for taking taxi rides or sharing the application so that’s good.