Sigh. You people are fucking exhausting. #5 of saying "you can't do that" and giving nothing more than "server can't handle it" as a reason, which is why I stated my credentials, because I'm sick of people talking out of their asses.

When the instance that wants to publish your work makes a call to the api, they have a domain referrer value. Being able to filter on that value is already in place through the process of defederation.

Filtering the output on that domain referrer value is neither some complex process, nor will it increase server load as you're reducing the amount of content the API is producing.

How do you think IP filtering works? Every public facing web service does it. This is the exactly the same thing, except that rather than blocking the entire site, you're blocking a small part of it. It's even easier than blocking a specific page to an IP, because you only have to block a subset of data coming out of the feed on the api.