Koa vs NestJS: What are the differences?

Developers describe Koa as "Next generation web framework for node.js". Koa aims to be a smaller, more expressive, and more robust foundation for web applications and APIs. Through leveraging generators Koa allows you to ditch callbacks and greatly increase error-handling. Koa does not bundle any middleware. On the other hand, NestJS is detailed as "A progressive Node.js framework for building efficient and scalable server-side applications by @kammysliwiec". Nest is a framework for building efficient, scalable Node.js server-side applications. It uses progressive JavaScript, is built with TypeScript (preserves compatibility with pure JavaScript) and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and FRP (Functional Reactive Programming) Under the hood, Nest makes use of Express, but also, provides compatibility with a wide range of other libraries, like e.g. Fastify, allowing for easy use of the myriad third-party plugins which are available..

Koa and NestJS are primarily classified as "Microframeworks (Backend)" and "Frameworks (Full Stack)" tools respectively.

Some of the features offered by Koa are:

• Provides 3 different kinds of functions as middleware
• common function
• async function

On the other hand, NestJS provides the following key features:

• Extensible - Gives you true flexibility by allowing use of any other libraries thanks to modular architecture.
• Versatile - An adaptable ecosystem that is a fully-fledged backbone for all kinds of server-side applications.
• Progressive - Takes advantage of latest JavaScript features, bringing design patterns and mature solutions to node.js world.

Koa and NestJS are both open source tools. It seems that Koa with 26.9K GitHub stars and 2.47K forks on GitHub has more adoption than NestJS with 18.3K GitHub stars and 1.31K GitHub forks.

According to the StackShare community, Koa has a broader approval, being mentioned in 62 company stacks & 170 developers stacks; compared to NestJS, which is listed in 19 company stacks and 70 developer stacks.