Does there exist any API to register the user on Constant Contact?
Is there any sample application for the same i.e. that create Constant Contact user account?
If you are a partner of ours, we do have an API that can create accounts under your partner account. If you want to learn more about this please email our AppConnect team. They are in charge of giving access to that API.
If you have any questions please let me know.
there are also these code samples :)
View API documentation, code samples, get your API key.