It is a free and open source JavaScript tech stack for building dynamic web sites and web applications.

The MEAN stack is JavaScript-based framework for developing web applications. MEAN is named after the 4 key technologies that make up the layers of the stack that are :

• MongoDB : document database — A No-SQL database good for horizontal scaling

• Express(.js) : Node.js web framework — Easiest way to start a server using JavaScript Server

• Angular(.js) : a client-side JavaScript framework — Powerful front-end framework

• Node(.js) : JavaScript web server

Advantages

• Mainly use to create cloud hosted applications

• MEAN stack applications are flexible, scalable and extensible, making them perfect candidate for cloud hosting.

• The stack includes its own web server so it can be deployed easily, and the database can be scaled on demand to accommodate temporary usage spikes.

Disadvantages

• JavaScript is a great modern language, but it wasn’t initially designed to build back-end servers. Since the foundation of the MEAN stack is JavaScript, including the back-end server, it might come with concurrency and performance problems at scale due to JavaScript nature