124 views | Last updated on Feb 14, 2017
99.96% for the last year. We're constantly working to improve it. In practice, this is better than most other sites, and well ahead of the industry average of 99%.
Those numbers are for our main US server, which is the most heavily loaded. We don't have exact numbers for our non-US servers, but since they are under less load, they have had better uptime than the main US server.