Over several years of phone usage, a lot of us may end up with scores of contacts in our phonebook with outdated information. A solution for iOS users is a free app called Addappt. It's a personalised address book which updates information with other contacts using Addappt. Like most apps, you have to invite people to connect with you on Addappt. As and when your connected contacts update their contact card with new information, Addappt will automatically update your devices address book and viceversa. At any time, you'll have the latest contact information about your friends and vice versa. The information updated happens within minutes and works seamlessly. One of the best features about Addappt is that it works within your device's default contacts app. The disadvantage is that it's currently only on iOS and both parties have to be using Addappt for it to work. Recommended for iOS users.