I'm trying to find out if installing WhatsApp will send the information of all my contacts to Facebook. The Usage of your phone number and address book FAQ page is not clear about that.
I can deny the app access to my contact list but that is counterproductive to using it. It's fine if WhatsApp accesses my contact list but I want that information to stay 'in my phone'.
Just as I do not allow Google or LinkedIn to collect my contact list, I also want to prevent my friends' information ending up in the Facebook databases (through me). After all, my friends never gave permission for that.
This is what the FAQ says about Usage of your phone number and address book, but that still does not answer my question:
WhatsApp uses the phone numbers from your phone's address book to provide you an up-to-date list of WhatsApp users you know to make it easier for you to message them via WhatsApp. WhatsApp regularly looks at the phone numbers in your address book and then checks to see which of those numbers are verified in WhatsApp. During this entire process, phone numbers are sent to WhatsApp for lookup, securely, over an encrypted connection. So that you know who you are chatting with, the app then displays the names from your address book.
Maybe superfluous to say: I do not have Facebook/Messenger installed on my (Android) phone.