My experiences from writing + running our tasks App backend ( <a href="http://tomorrow.do/" rel="nofollow">http://tomorrow.do/</a> ) on Heroku:<p>1. Node.js + expressjs is quite an efficient option for serving API and the static site on Heroku, only the single free dyno is needed for over 3 million installs and peaks of 30-40k site visits. Only rarely have we needed a second or third dyno under an extremely heavy peak traffic period.<p>2. A commercial CDN is a good and not too costly option for static files ( <a href="http://maxcdn.com" rel="nofollow">http://maxcdn.com</a> )<p>3. AWS database + file services like DynamoDB/S3 are not that flexible but aren't too expensive, pretty much scale up and down without you doing too much and don't go offline much at all