When comparing NestJS vs Koa, the Slant community recommends NestJS for most people. In the question“What are the best backend web frameworks?” NestJS is ranked 23rd while Koa is ranked 33rd. The most important reason people chose NestJS is:
There is a lot of cool stuff, like decorators, full-fledged object-oriented programming and static types.
Specs
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Pros
Pro Uses Typescript
There is a lot of cool stuff, like decorators, full-fledged object-oriented programming and static types.
Pro Modern
Allows you to structure your code using modern concepts.
Pro Allow access to express middlewares
Pro Generator support from ground up
Using generators (a bleeding edge feature, even for Node.js) would clean up your code from the mess caused by all those callbacks; making your code more manageable.
Pro Extremely lightweight
Koa is very lightweight with just 550 lines of code.
Pro async/await keywords are supported and has transcended beyond generator functions
Generators functions are of course a huge plus, but at the time Koa team has transcended generations functions and shifted towards async/await style programming. It has made the Koa best framework available in the market.
Pro Development team has a proven track record
Koa is developed by the team behind a widely used node.js framework (express.js).
Pro Built for ES6
Cons
Con Few examples
Con Community is relatively small
Con Not compatible with express style middleware
Koa uses generators which are not compatible with any other type of Node.js framework middleware.