I am searching for the similar thing and can't find anything...

Is it possible to handle all of this in nginx? ( Seting/evaluating headers, limiting connection, IP whitelisting ) ?

https://developer.github.com/v3/rate_limit/

I want to throttle access to our API and send extra headers, based on the limit say 100 req / minute for 1 IP you would get a 429 HTTP error code ( Too many requests ) and extra header X-RateLimit-Reset: would state how much time left until limit will expire.