The ingenious Addappt resolves the issue of having outdated contact details by having each individual person manage their own contact card. After you install this app, whenever one of your contacts who also uses Addappt changes a bit of information on his or her contact card, that information is seamlessly pushed to all of their contacts within the app.
Contacts integration: Addappt uses the built-in contacts database, thus ensuring that any changes your contacts make on their end will propagate all the way to whatever cloud syncing solution you might use.
Lightweight: Less than 3MB in size, this free app runs extremely well on all iOS 7 devices. The modern and clean interface has the majority of options you would need in such an app.
Valid email required: Despite adding just one extra step to the setup process, the need to verify your email address does make the initial experience a bit jarring.
No back gesture: If you've come to expect the ability to swipe from the left side of the screen to go back a page, Addappt will leave you disappointed.
Only useful if your contacts use it: In order to fully benefit from the service, you need all your contacts to start using the app. What's more, it offers virtually no contact management except for your own card.
On the face of it, Addappt turns out to be a great contacts syncing solution. However, it runs into the same problem as many messaging networks -- if your contacts are not using the app it won't do much good for you.