|Google Cloud Platform|
This was recently put to the test when a post about the World of Warcraft Predictor made it to the top of the WoW subreddit; a community with thousands of active users at any time. The result was hundreds of users suddenly pouring onto the site. I carefully monitored the error logs and performance stats, holding my breath in anticipation of performance issues or website hiccups. However, App Engine was able to seamlessly spin up a number of new virtual servers to handle the extra traffic.
Performance remained very steady, with the exception of a possible memory leak that caused some virtual servers to shut down. Even in that scenario, I was pleasantly surprised to discover that App Engine is nice enough to wait until the server is done handling requests, before shutting it down. This only resulted in a few users using having to wait a couple seconds for a new server to start up.
P.S. Google isn't paying me to write this, and I don't think App Engine is perfect. I'm just happy that my website can handle a lot of traffic without shutting down, and that I don't have to pay for it every day.