Can Apptoto use my Google contacts?

Yes, if you prefer to keep phone numbers and email addresses in your Google Contacts, Apptoto can use them to perform reminders. Apptoto will try to link appointments and contacts by searching the appointment for Properly Cased names, phone numbers, and email addresses.  If it finds a contact record with any of those matching points, then it will use that contact's information when sending messages. It will also consult the appointment's guest list to see if any contact's email address is listed as one of the guests, and will then link that contact to the appointment.