We do have an API for partners that allows them to create Constant Contact accounts, however this does require you to be an active member of one of our partner programs. Can you share a little more how you would create the accounts and why you're looking to create accounts programatically?
Are you going to be reselling Constant Contact to multiple customers and need to customize this reselling experience or is this for just other users at your company for a single Constant Contact account?
We have Retention Management account under that we have multiple Client, for that client we want to give some privileges to access the page, upload list or other control.
At this time, we don't have any way to limit access to different areas of an account, either through the API or in our UI. We recently launched our MultiUser feature, which allows for creation of multiple user logins for an account. We are looking at adding role based functionality to this feature in the future, but this is currently not available either through the UI or the API.