Koa.js

Koa is a new web framework designed by the team behind Express, which aims to be a smaller, more expressive, and more robust foundation for web applications and APIs.

There is no internal routing package in koa.js. koa.js does not support internally routing. But it provides external router package. The user has to include the external third party package in routing. Express has built-in routing package which is express.static to serve the static content and express also have JSONP.

The reason that they didn't include those features in the koa.js is they want to koa.js to be fast. Purpose of koa.js is to make faster node.js framework.

How is Koa.js different from Express

• Promise based flow : no need to work with callbacks here.
• No callback hell : they provide async/await
• Better error handling through try catch block 
• Koa.js is more modular
• Proper stream handling 
• better user experience