uses a fairly standard LAMP stack. That is to say MySQL for the database, PHP for the server side code. Apache doing the web serving. And everything running on Linux. We’ve also got a small daemon written in C++ which interfaces with our internal data stores to serve up the tiles and meshes. For the most part, the PHP is a pass-through though it also handles a little session data and some database stuff. Most of the database operations are done in stored procedures. We also use Node.js with web sockets for live updates and chat.