So we have this situation where we're really integrating into a platform where the user can choose between multiple services. It's an ecommerce platform and each client will have a different URL.
For example, site1.platform.com will be separate from site2.platform.com. I looked at using OAuth 2.0 for it, but the Redirect_URI will need to be different for each so that won't work. What would you recommend for this? We have considered registering a new app for each site that uses Constant Contact (some will use different email services), but I wondered if there was a more "official" solution to this.
Currently with the v2 API registering different API keys so each one can have its own redirect URI would be a viable solution. You could also use just one redirect URI and from there link to each of the individual apps.
When we release our v3 API it will support multiple redirect URIs. We do not have an exact date on the release, but we are hoping it will be within the next few months. Keep an eye out on these forums; also watch developer.constantcontact.com for an update.