Get the Act! CRM SDK for Desktop
and Act! CRM API for Act! Advantage here...
I was going to make this a download file.
Then I found the webpage where ACT CRM has all the SDK for Desktop here:
https://www.act.com/dps/sdk/v22.1/
You can find all the API for Cloud/Act! Advantage online here:
https://www.act.com/developer/