(Slightly related to this question: Questions of the form: Does {website X} have an API?)
Application Program Interfaces are firmly in the domain of programming. Except, perhaps, for questions asking where to find a particular web app's API, questions about APIs are going to be off-topic here.
Given that, api looks like it fits the definition of a meta-tag. We don't allow general API questions, so it can't work as the only tag on a question. It will need to have the context of the web app being asked, and presumably a tag for that will be on the question.
So I think we should remove it from the 74 33 questions where it currently exists.
