sails

Sails.js is a web framework for building back-end applications in JavaScript using Node.js. A web framework is a toolkit that handles the repetitive parts of building a web server — routing requests, talking to databases, handling authentication — so developers can focus on their specific application logic.

The problem it solves: building a web server from scratch involves a lot of boilerplate code. Sails follows an MVC pattern (Model-View-Controller — a common way of organizing code where data, display, and logic are kept separate) to give structure to your app. It is particularly aimed at apps that need real-time features, like live chat or collaborative tools.

How it works: you define data models (describing what your data looks like) and Sails automatically generates API endpoints for creating, reading, updating, and deleting that data. It also builds in real-time communication using WebSockets — a technology that keeps a persistent connection open between the browser and the server, so data can flow both ways instantly without the page refreshing. You can connect it to several databases including MySQL, PostgreSQL, MongoDB, and Redis.

You would use Sails when building a Node.js web API or full-stack app that needs real-time features, and you want a structured framework rather than assembling everything from scratch.

The tech stack is JavaScript running on Node.js, built on top of Express and Socket.io.