Before writing more about this application, just one thing. The first line in the description of this application says
Download while it is still free for a few more days...
So they may be going to make it a paid app, so get the application before that, if you are interested.
This application will help you to manage your contacts. The features are
Find and Remove duplicate contacts
Merge contacts between accounts
Format phone numbers
Find incomplete contacts
Clean the empty fields
Add international prefixes to numbers
Find the numbers not saved to contact list from the messages.
Mass Delete contacts
The chances of duplicate contacts will be high if you have saved many in to your contact list. Contacts Optimizer can find them easily and can also remove them for you with ease. If you have more than one accounts you can easily merge them and then find and remove the duplicate to have a clean and tidy contact list.
Get this from Google Play Sore