node.js itself includes a web server, or more accurately, node is a framework for developing servers. It's very popular for web development these days.

Typically you don't write servers in node directly. Express is a popular web application framework built on top of node, there are also others with different designs and philosophies.

You can also use MongoDB, which is a JSON (BSON more accurately) data store, where stuff like stored procedures and queries are themselves written in JavaScript. So you can have JavaScript from top to bottom.