Pinterest.com has grown to billions of page views per month in just under a year, and the number one question we're asked at parties is "what's in your stack?" Sit back while we take you on a tour of our current architecture, the lessons learned along the way, what worked and what didn't work. We'll focus on how things changed as we grew, how we sharded our MySQL database, caching mechanisms and server management. We'll also touch on the conveniences and challenges of building today's most modern web infrastructures on Amazon's EC2.