Since it &quot;just&quot; mirrors your phone it shouldn&#x27;t access your OSX address book.<p>But since most people use iCloud to sync that address book with their Mac and their phone its moot. If you open WhatsApp on your phone, it will take a trip through your contacts and upload everything to their servers. Which, I still maintain, is stupid and unnecessary and the numer one reason why I never bothered with WhatsApp.<p>It&#x27;s an IM client. So let me put my numer in and that&#x27;s it. If I want to use it, I probably already know the people that also use it. So if they in turn also hae uploaded their number, I could search for it and add it. Have them confirm out connection and chat away. There is no need to grab all my contacts&#x27; information without their consent.