GitHub - dansingerman/app-engine-headers: Google app engine application that is the server side counterpart to https://github.com/dansingerman/jQuery-Browser-Language

You can use it to retrieve any http request headers via JSONP.

You can also get useful geolocation headers that Google App Engine provides.

gimme_headers({
  'Accept-Language': 'en,en-US;q=0.8,fr-CA;q=0.6,fr;q=0.4', 
  'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8', 
  'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.90 Safari/537.36', 
  'Host': 'ajaxhttpheaders2.appspot.com', 
  'X-Appengine-Region': 'eng', 
  'X-Appengine-City': 'croydon', 
  'X-Appengine-Citylatlong': '51.376165,-0.098234', 
  'Content-Type': '; charset="utf-8"', 
  'X-Appengine-Country': 'GB'
})