I built fetch-robot (https://github.com/krakenjs/fetch-robot) to avoid dealing with CORS preflight requests. And the associated maze of request and response headers you need to use to negotiate in the preflight.
This is pretty great. We have a number of applications that have different API and frontend origins, and it's frustrating to see that every request needs another roundtrip.
So I started thinking about how we did things pre-CORS and I've been wanting to build this frame-proxy in our API. Pretty helpful!
