Hello SunnyB44,
Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.
An app developed using our API can be used by any Constant Contact account holder, if the developer chooses to share their app. In our documentation, when the term "user" is used in the OAuth description, this is referring to the Constant Contact account holder who is authorizing the app to access their Constant Contact account.
If you were to develop a sign-up form for your website using Constant Contact’s API, you would be both the developer and the user of the application. Your website visitors who are signing up through your form wouldn’t directly be “users” of the app, they would simply be providing the data (by filling out the form), which the app would then send to Constant Contact.
I hope this helps to clarify the OAuth2 authorization steps.
Please have a look and let us know if you have any other questions!
Regards,
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