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29 July 2023 - 7 minutes

How 10 Major Companies Are Using JavaScript

You know it’s popular, but do you know just how many companies are using it? 

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There’s no denying that JavaScript is everywhere and the vast majority of companies are using it on a daily basis. After all, this scripting language is widely used; are you interested in understanding how it’s used by some large businesses? Well for these 10 companies, JavaScript is immensely important and that isn’t going to change any time soon.


Okay, we’ll admit it: you’re probably not going to find JavaScript powering Windows anytime soon, but Microsoft relies on JavaScript for a whole lot else: 

  • Microsoft works closely with JavaScript to build its Edge web browser. 

  • All browsers need to process and execute JavaScript efficiently, so Microsoft has developed and maintains its own JavaScript engine for Edge. 

Recently, Microsoft has really embraced NodeJS, thoroughly supporting Node on the Azure cloud platform. It's one of Azure’s major features and they’ve integrated Visual Studio support for Node. Microsoft has also developed a version of Node for Internet Of Things (IoT) applications, which is great because it’s lightweight and efficient.


PayPal has been using JavaScript on the front end of their website for a long time, but that’s only the beginning:

  • The online payment giant was one of the earliest adopters of NodeJS and during an overhaul of their account overview page, they decided to try building the page in Node at the same time as their usual JavaScript development. 

  • The NodeJS version worked out so well that they chose to use it in production and build all client-facing applications in Node going forward. That means that most of what you see in your account is running on Node.

PayPal even went as far as to create and maintain their own version of Express, called KrakenJS


Like PayPal, Netflix started out using JavaScript for just about everything. They too ran into problems with JavaScript’s size and the time it required to develop: 

  • Over time, Netflix moved away from its more traditional structure into the cloud and started to introduce NodeJS. With NodeJS, Netflix was able to break down pieces of their user interface into individual services. 

  • This more distributed approach was able to speed things up and alleviate stress on their servers and today, a large portion of Netflix’s interface is running on Node.


Groupon used to be infamously slow. Why? They were powered by Ruby on Rails. That’s the same framework that brought you the Twitter fail whale: Groupon was all one gigantic Ruby on Rails application:

  • Thanks to difficulties in speed and maintainability, they decided to change over to NodeJS. 

  • Node allowed Groupon to rebuild their entire US website by breaking down everything into individual NodeJS web applications. 

  • Groupon is now made up of over 20 Node applications and it moves much faster as a whole.

Groupon is currently moving all of their international sites to NodeJS and has joined the NodeJS Foundation. 


Uber needs to handle loads of data in real time; they receive millions of simultaneous requests, and that’s not just hits on a page. Uber needs to track driver locations, rider locations, and incoming ride requests. It has to seamlessly sort that data and match riders as fast as possible:

  • All of that plays to NodeJS and JavaScript’s strengths. 

  • Node is designed to handle requests and hand off data quickly; its asynchronous capabilities are a huge part of that. 

  • Node is central to Uber’s user-facing stack for just that reason.


You’re probably aware that Facebook uses JavaScript, but what’s probably not as obvious is exactly how much JavaScript goes into making Facebook and how much Facebook is involved in JavaScript development. Try disabling JavaScript in your web browser and going to Facebook. The website will actually stop you from logging in because it won’t work without JavaScript:

  • You may have noticed the way that Facebook loads: each piece of the page is separate. Facebook has invented its own way of breaking down and delivering sections of JavaScript separately. 

  • Each section of your Facebook page is a collection of independent JavaScript applications. It doesn’t stop there. 

  • Facebook created React, one of the most popular front end frameworks. Facebook uses React on, as well as Instagram and WhatsApp.


How doesn’t Google use JavaScript?! Seriously, it’s everywhere:

  • Google’s search results use JavaScript. 

  • The Gmail web client is powered by JavaScript. 

  • Google Docs? Yeah, that’s JavaScript too, compiling JavaScript into a lower-level faster form more suited for rich and highly responsive web applications. 

  • Chrome, as a web browser, needed a JavaScript engine, so Google also made V8. V8 not only powers Chrome, it’s also at the heart of NodeJS. Without Google, there would be no Node.

Google develops and usually open-sources its own JavaScript tools, such as AngularJS, which is used most prominently in Google’s DoubleClick advertising platform, but it’s also one of the most popular front end frameworks available. It’s even part of the MEAN stack.


eBay’s story is a lot like Netflix’s. For a long time, just about everything in eBay’s tech stack was based on JavaScript. A few years ago, eBay encountered a problem for which JavaScript wasn’t the right solution. They decided to give NodeJS a shot instead:

  • Node worked so well that eBay not only kept using it for that particular service, but also began migrating their entire user-facing stack to NodeJS. 

  • Just about everything that you interact with on eBay is powered by Node. 

  • Beneath Node, JavaScript is still dealing with their databases, but eBay places a lot of trust in NodeJS.


Most people probably don’t think of Walmart as a tech company, but because they’re one of the largest retailers in the world, their online retail business is gigantic. It’s not much of a stretch to understand how they need to build a technologically advanced web application to drive their online business:

  • Walmart started out with JavaScript, a solid, enterprise-grade platform that has been the de facto choice for years. 

  • However, Walmart needed something faster and lighter weight for their mobile site. So, they turned to NodeJS.

  • Walmart began to see Node as a valid JavaScript replacement in loads of other places and today, the that you see is powered by Node. 

NodeJS was also the ideal choice for other web applications within their marketplace that require multiple users to be able to access management interfaces simultaneously.


LinkedIn relies on NodeJS for its mobile site and a few years back, LinkedIn used Rails for its mobile site. As with other large Rails applications, it was slow, monolithic, and it scaled poorly:

  • LinkedIn switched over to NodeJS to solve its scaling problems. 

  • Node’s asynchronous capabilities allowed the LinkedIn mobile site to perform more quickly than before while using fewer resources. 

  • Node also made data sharing and building APIs easier for the LinkedIn developers.

JavaScript Is Everywhere!

These are only 10 examples, but you can certainly find more. So much of the web runs on JavaScript, it’d be much harder to find a company that doesn’t use JavaScript in some way.

These companies are among the largest tech companies in the world and many are also running the largest production deployments of NodeJS; the others are responsible for important parts of the JavaScript ecosystem as a whole.

If you want to jump aboard the JavaScript train and use your knowledge to transform your career, there’s no better place to start than Ironhack. Our Web Development Bootcamp will prepare you with everything you need to start working in web development, taking advantage of all that JavaScript has to offer. 

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