Remove Duplicate Contacts is an iPhone app that helps users to quickly backup their address book, remove duplicate contacts, and merge related contacts. Developed by Zhong Zhang, this app has become quite popular, ranking as the top overall #1 in France, Belgium, Madagascar, and top productivity #1 in Hong Kong, Taiwan, and other countries in March 2012.

Users have praised the app for its convenience and efficiency. One user, Holly lecl, described it as "Very convenient and efficient," while G. House MD exclaimed, "WOW...Simple and worked in seconds!!!". The app's smart check duplication and related feature, which supports merge with photo, first name, last name, company, job title, phone number, email, URL, address, birthday, social profile, instant message, and notes, has also been commended.

Other features of the app include support for backup and restore address book, auto delete duplication contacts, merge related contacts, delete and merge contacts manually, and save backup at local or export by email. It also supports many contacts sources like iCloud, Facebook, Gmail, Yahoo!, and Exchange, and works on both iPhone and iPad.

Overall, Remove Duplicate Contacts is a simple and easy-to-use app that helps users keep their address book organized and free of duplicates.