Web Development

Balling the Koa vs. Express Scenario in Node.js Frameworks

August 20, 2019

Every developer steps ahead after having a decent understanding of JavaScript. Extending the same knowledge, the emergence of Node.js has enabled front-end coders (who used to make use of JavaScript only) to adopt back-end coding equally well. Full-stack developers have adopted Node.JS + MongoDB + Angular.JS or React well. Node.js is designed to be lightweight and provides only fundamental functionalities as a web server to boost web application development speed. This comes as an example of one of the dependable npm packages. Moreover, Node.js comes along with simple architecture and scalability, is an event-based and non-blocking driven server that is capable of handling a large number of real-time users.

Understanding Node.JS

Node.js is a fast and scalable option for medium sized to large network applications based on event-driven non-blocking input/output model that makes use of synchronous programming. It is a mobile and web application framework that is a combination of libraries, helpers and tools to provide a way to effortlessly build and run web and mobile applications. A web framework lays out the foundation for building apps or website with its architecture and features like flexibility, extensibility, security and compatibility with other libraries, etc. There is always some kind of generic implementation that is unique to the framework for every Node.js function which would then require the user to follow the lead of the framework by adding more codes to define its use cases.

Benefits of Using Node.JS Frameworks

Being at par with other JavaScript frameworks, web developer India prefers Node.JS frameworks due to their productivity, speed, and scalability. Besides this it provides a set of tools, guidelines and recommended practices that allow developers to write code for both front-end as well as the back-end, thus maintaining the coding pattern all through. In this way, this can eventually help strengthen the coding standards across the team of developers.

Is it easy to select an appropriate Node.JS Framework?

A framework can be difficult to select and subjective to its use-case. A developer normally selects based on the features that we like. Most of it often depends upon the weight of the framework of the application, simplicity, speed, learning curve, configuration, and flexibility. In other cases, GitHub stars can be useful for making a quick decision.

Top Node.JS frameworks in 2019 include Express.JS, Socket.io, Meteor.JS, Koa.JS, Sails.js, MEAN.io, Nest.JS, Loopback.io, Keystone.JS, Feathers.JS, Hapi.JS, Strapi.io, Restify.JS, and Adonis.JS; all these help boost productivity while building JavaScript application, especially on the server-side. Stars aren’t everything so we’ll be organizing by what we’ve seen to be popular on ADA blog:

Node.JS Framework#1: Express.JS

It is fast, non-opinionative and minimalist web framework for node. It has 45,028 stars on GitHub (as of August 2019) and around 8MM npm weekly downloads. It behaves like a middleware to help manage servers and routes. Set of routing libraries, powerful collection of frameworks and focus on high performance, a multitude of easy to use HTTP utility methods, middleware and functions enable developers to easily write robust APIs.

Writing a simple program to print “Hello World”

const express = require(‘express’) const app = express() const port = 3000 app.get(‘/’, (req, res) => res.send(‘Hello World!’)) app.listen(port, () => console.log(`Example app listening on port ${port}!`))

Advantages of Express.JS

  • js is easy to configure,
  • Eases Node.js web application development
  • Allows defining routes of the application based on HTTP methods and URL’s
  • Includes various middleware modules which can be used to perform additional tasks on request and response
  • Is easy to integrate with different template engines like Jade, Vash, EJS, etc
  • Allows defining error handling middleware
  • Allows creating REST API server
  • Easy to connect with databases such as MongoDB, MySQL, and Redis
  • Focusses on browsers thus easing out the way templating and rendering is done.

Disdvantages of Express.JS

  • It is difficult to refactor as program complexity increases.
  • Event-driven nature (callbacks)
  • js chains middleware routines into custom request/response pipeline. This pipeline includes headers and the body.
  • Code organization is represented in the form of patterns (for easy maintainability)

Where is Express.js suitable?

  • Suitable for applications which communicate with third-party resources
  • For building applications to monitor visitor’s actions.
  • For creating real-time applications like voting/polling.


Express has a thin layer of fundamental web application features (without neglecting Node.js) features. Some of the best practices for improving Express performance includes:

  • Making use of Gzip compression
  • Not making use of synchronous functions
  • Making use of debug module for debugging
  • Handling try-catch exceptions properly
  • Running the app in a cluster
  • Handling cache request results efficiently so that the app does not repeat the operation to serve the same request repeatedly
  • Making use of a load balancer to run multiple instances of it and distribute the traffic.
  • Using a reverse proxy that performs supporting operations on the requests, handle error pages, caching, compression, serving files and load balancing among other things.

Node.JS Framework#2: Koa

Koa can be called as an extension of Node.js, which aimed to replace Node.js. Built by the same team behind Express, is quite smaller, lightweight, much more expressive, has a robust foundation for web applications and API’s.

Koa leverages asynchronous functions, chucks callbacks and increases error-handling significantly. It does not chains or bundles any middleware routines within its core and provides an elegant suite of methods that smoothens writing servers. But it acts as an object containing an array of middleware functions which are composed and executed in a stack-like manner upon request.

Writing a simple program to print “Hello World” in Koa

const Koa = require(‘koa’); const app = new Koa(); app.use(async ctx => { ctx.body = ‘Hello World’; }); app.listen(3000);

Features and Advantages of Koa.js

Primarily, Koa.js allows programmers to get rid of callbacks. In case one wishes to be closer to the old programming style, Express.js turns out to be an option. But in other cases, Koa answers improved interoperability, robustness, helpful methods, lightweight code, error handling, generated based control flow, facilitating and upstream and downstream flow of control, cleaner and more readable async code.

Koa has much different design and is fundamentally a large departure from what Express.js is meant for.

  • Callbacks are not required.
  • Better error handling through try/catch.
  • There is no need for domains.
  • Koa does not include any middleware.
  • Proper stream handling.
  • Koa is more modular.
  • Koa makes use of body parsing function.
  • Less likely to be hacked.
  • Provides better user experience.

Disadvantages of Koa.js

  • Koa generators are not compatible with any other type of Node.js framework middleware.
  • Koa is not compatible with Express style middleware.
  • Open-source community is relatively small as compared to Express.js.


Koa eases code management process, is lightweight, and makes use of asynchronous API’s in the code, keeping the code small, light, making use of GZip compression.

Chalking out major differences: Express vs. Koa

Differences Koa Express
Middleware Kernel The core Koa module is just the middleware kernel. Express includes complete application framework featuring routines and templates.
Replace vs. Extend Koa replaces context object ctx entirely. (ctx request and ctx response). Express augments and extends native Node.js req and res objects.
Asynchronous/Await vs. Callback Koa takes advantage of new async/await keywords. Express is callback oriented.
Routing No routing Has routing
Convenience Facilities (sending files) Not provided Is provided
Templating Not provided Is provided
JSONP Not provided Is provided

Find out which Node.js Framework blazes out? Koa vs. Express

While Koa aims to fix and replace Node.js, Express aims to augment Node.js. Koa is designed to efficiently handle callbacks and handle the error. It brings out its ctx.request and ctx.response objects instead of Node’s req and res objects. Express brings up some additional features to enhance the features of Node.js and include features like routing and templating contradictory to Koa. Thus Koa can be seen as an abstraction of Node.js HTTP modules, while Express is an application framework for Node.js.

Top web development companies need to consider the following points before selecting a framework from Koa or Express:

  • Are you creating this application as an extension to existing Express.js file?
  • Is the performance of the application important?
  • In case you require to make use of complete framework without having to pull in multiple dependencies, Express must be preferred.

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