Cleaner - Merge Contacts 4+

The free version of app itself is a full utility if you are willing to do the tasks on your own. The developer has gone that extra mile to come up with smart filters with exactly what one would need to clean the contacts.
Deserves 10 star ⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️

started getting a lot of Half crashes.
App doesn't quit completely but goes back to the home screen and runs in the background but does not complete.

let's be straight up here. you can really only use the multiple delete function of this app when you download it, and all of the rest of the functions are just demos of what you get when you pay. however this seems to be a highly rated, and well functioning application. i'm sure there are plenty of other ways to merge contacts without paying, but being frustrated in doing so made this app worth the purchase for how well thought out it is. I originally only downloaded it for a way to quickly delete all the contacts I no longer had a need for, but soon discovered just how screwed up my contact information and duplicates ended up after years of an organized use.

Because of a sync bug with a CRM add-on, my contact database should have been around 5500 but had grown to over 12,000. I would have been almost impossible, but certainly horrible to clean this up manually.

I paid the $3.99 or whatever for the full boat version and began cleaning up my mess of duplicate contacts. The program does what it should and I’m happy. One limitation I noticed was it wasn’t able to handle more than 701 duplicates at a time. I found I needed to rerun each clean-up multiple times until the program found 0 contacts that met the duplicate search criteria I was using. If you’ve got a stupid amount of duplicates like I did, keep an eye on this and make multiple passes.

Good luck!