Express.js is a front-end or backend framework?
Express.js is a JavaScript backend framework. It is mainly designed to develop complete web applications (single-page, multi-page, and hybrid web applications) and APIs. Express is the backend component of the MEAN stack where M stands for MongoDB, which handles database; E stands for Express, which handles backend; A stands for AngularJS, which is for the front-end, and N stands for Node.