Is there a way (through the API) to get the total number of contacts in my account? Also, what happens if I add contacts via the API and then go over the maximum number of contacts in my subscription? Currently set to 10,000 contacts.
As of right now, there isn't a way to get the number of total active contacts in your account. There is a way to get the number of contacts in each of your contact lists though. The ability for a contact to be in more than one list in your account will prevent the total active contacts from being the sum of contacts in each list, unless you only have one list, or are sure to make all of your contacts unique to each list.
API Support Specialist