Nginx talk HTTP and REST api talk HTTP so making them collaborate is very easy.
- proxying: you can set up a http proxy to an external api via your server. The client side can do call to your server with all the remote / proxyied api methods
- caching: this way you can follow external api rate limits with caching request on your nginx
- timeout: you can degrade with a short timeout: better than letting the user waiting more than 30 seconds
- private keys: your js code don’t embed private api key, its rewritten / added on the fly by nginx.
- json to jsonp: rewrite the api response to make it jsonp allowing cross site calls