Node.js is a popular cross platform, open-source, runtime environment used to build back-end applications, using JavaScript outside of the browser. Node.js operates on a single threaded architecture, using non-blocking I/O calls held in event loops to enable the processing of thousands of concurrent connections and requests.

While Node.js is versatile and widely used, it’s not a one-size-fits-all solution. Node.js is built with specific needs in mind and excels in areas such as developing real-time push-capable applications. Through low latency and an ability to serve a huge number of concurrent requests while maintaining a high throughput, Node.js is fantastic for building fast and highly scalable applications.

Built on Chrome’s V8 JavaScript engine and designed to run web applications outside of the client’s browser, NodeJS is used for server-side programming. Since every browser has a JS engine, Node.js allows for unified maintenance, running, and development of whole sites.

A brief history of Node.js

At around half the age of JavaScript, and around 20-years younger than the web itself, Node.js is by no means a new technology. Before its creation, existing web servers had a hard time handling and processing large volumes of concurrent requests. As such, building engaging and easy to scale products that could support high volumes of users was a major issue facing many businesses.

Key Properties of Node.js

Node.js is made up of several key concepts that heavily influence when and where it’s best used. Node.js is not a magic bullet or solution. Instead, its best use-cases maximize Node’s strengths, while minimizing the impact of its weaknesses. Here we explore concepts including Node’s event-driven I/O architecture, single threaded event loop, asynchronous processing, and more:

Key Concept Description
Event driven Event driven programming is a paradigm in which the flow of the code’s execution is determined by events. Events can be user actions such as clicks and input from sensors. Applications that use event-driven programming are designed to respond to user engagement and actions.

Since Node.js uses event-driven programming together with its asynchronous architecture, it’s ideal for processing high-volume concurrent user connections and requests.

Single threaded JavaScript runs on a single thread based on Node.js’s single threaded event loop architecture; which is designed to handle multiple concurrent requests. Single threaded means that the processes are executed one command at a time. While Node.js uses several threads, it has only one executing thread to perform operations.

Node.js uses the event loop to execute non-blocking I/O operations, enabling it to execute commands asynchronously. This way, longer I/O operations can be put aside to execute other commands, even with a high-volume of user requests.

Asynchronous Node.js is asynchronous by default, allowing the efficient processing of multiple requests. Asynchronous operations enable more time-consuming tasks to be executed without blocking the calling thread while the operation competes. As such, other blocks can be processed while awaiting the result from the previous operation.

Node.js is best used asynchronously due to its single-threaded execution. It’s why Node.js is used effectively for applications that deal with high volumes of user actions.

Open source Node.js is open-source and free to use. You can download Node.js directly to your computer and start building applications right away. Most Node.js projects are also open source and frequently used by enterprises for their own projects, tools, and applications.
NPM NPM stands for Node Package Manager. It’s installed on your computer when you install Node.js. NPM is the manager for thousands of free to use, downloadable Node.js packages and modules. 

NPM is highly configurable, managing conflicts and discrepancies, letting you more effectively develop and install Node.js programs and applications.

MIT License Node.js is under the MIT license, which is highly permissive, allowing users to copy, modify, distribute, merge, publish, and even sell copies of the software. Anyone that has a copy of Node.js has the right to reuse the code for any purpose.

How does Node.js work?

Node.js is a runtime environment that runs on the Chrome V8 Engine, which converts the JavaScript code into machine code. As a runtime environment, Node.js can execute JavaScript code in real time outside of the browser – enabling developers to use JavaScript for server-side programming, for example.

Traditionally, JavaScript could only be executed inside the browser – and each browser had a different JS engine. As mentioned above, Node.js runs on the Chrome V8 Engine, freeing it from needing to be executed solely in-browser.

As a result, Node.js can be used to build whole platforms in a unified stack from frontend to backend with JavaScript – something that makes building and maintaining applications more efficient and streamlined. Below we’ll look at two important aspects of Node.js’s functionality.

Non-blocking, asynchronous operation

Node.js is under the MIT license, which is highly permissive, allowing users to copy, modify, distribute, merge, publish, and even sell copies of the software. Anyone that has a copy of Node.js has the right to reuse the code for any purpose.

Single threaded event loop architecture

Node.js’s processing model is based on JavaScript’s event-based model and callback function, allowing the handling of high-volumes of concurrent requests. Node.js’s architecture can split into the following components:

Node.js server

Node.js has a server-side platform that receives and processes users’ requests, returning the results correspondingly to each user.


Requests are either blocking or non-blocking depending on what the user is trying to do in a web application.

Thread Pool

The thread pool contains all of the available threads for executing tasks and fulfilling user requests. In Node.js, there are two types of threads; the event/main loop, and a pool of worker threads. These worker threads process longer-running operations without blocking the main thread.

Event queue

Node.js’s server holds received requests in the event queue, assigning them to the main event loop to be processed when its call stack is empty (i.e., when there are no ongoing operations)

Event loop

Node.js event loop is an endless loop that awaits pending tasks from the event queue, executes them, and returns the result. The event loop will sleep when its call stack is empty and there are no pending tasks held in the event queue.

Node.js workflow example.

Using the Node.js architecture, here’s an example of a simple Node.js workflow:

1- Client sends either a blocking or a non-blocking request to the web server to interact with the web application. Examples of requests include querying the database, updating data, deleting data, etc.

2- The server running Node.js receives the incoming requests and adds them to the event queue.

3- Requests held in the event loop are passed one at a time to the event loop

4- The event loop checks whether the requests require external resources (e.g., data storage, computation, etc.) and processes the task accordingly:

    • Simple, non-blocking requests are processed by the event loop and the result is returned to the client immediately
    • Complex blocking requests are assigned to a single thread from the thread pool, processed, and a result is returned upon completion.

5- Completed tasks are passed back to the event loops, which sends the response back to the client.

Should you use Node.js?

Node.js only exploded in popularity in recent years, despite having been around since 2009. JavaScript was widely used for front end web development, with platforms like Node.js unlocking whole new areas of application.

While both JavaScript and Node.js are broadly used today, they are by no means a one-size-fits-all solution. Node.js comes with a host of pros and cons, preferred use cases, and is more effective in certain applications.

Advantages of using Node.js

Node.js is a runtime environment that runs on the Chrome V8 Engine, allowing it to execute code outside of the browser. Node’s versatility and scalability are largely due to being non-blocking I/O, event driven, and with the ability to concurrently process high volumes of requests at the same time.

Fast performance

Node.js is particularly fast for web applications that spend a lot of time requesting information from the database or waiting on the network. Running on Chrome’s V8 Engine, implementing dynamic languages like JavaScript is efficient and quick as the engine compiles JavaScript into machine code. Node.js is highly event-driven, which along with its asynchronous, non-blocking I/O operations, makes it very fast.

Highly scalable

Node.js uses a single thread to handle non-blocking calls, allowing it to handle high volumes of concurrent requests without overwhelming system resources. Scaling applications from a small number of requests to thousands of requests is one of Node.js’s best use cases.

No buffering

Node.js uses the callback function to output data in blocks. This cuts down on processing time and the user doesn’t need to wait for the whole operation to complete before receiving the data.

Full Stack JavaScript

Developers can build both the backend and frontend of applications using JavaScript since Node.js allows them to program a web server, for example. Businesses can build cross-functional teams with full stack capabilities, leading to smoother collaboration between small and large teams alike.

Large and active community

Node.js and JavaScript have one of the largest and most active communities among modern technologies. Developers have access to NPM and vast libraries, making the learning process quicker and development more efficient.

Drawbacks of using Node.js?

Node.js isn’t a magic bullet that excels in every use case. There are some situations and applications that don’t suit Node.js’s properties and advantages. Below we explore some of Node’s potential drawbacks and some limitations to be aware of.

Not ideal for long-running CPU-bound tasks

As a single threaded runtime, Node.js’s performance is reduced when handling computationally heavy requests. Node will use any available CPU space to process the heavy CPU-bound request, blocking the event loop, and slowing down overall performance. While this can be dealt with by spawning worker threads (to an extent), it’s not ideal for large-scale use cases. Small and frequent delays compound to significantly slower processing at scale.

Vulnerability with NPM dependencies

NPM dependencies are all the other packages required for your app and its installed libraries to work properly. It’s estimated that around 15% of all NPM packages have known vulnerabilities, and that ~76% of Node shops use packages with vulnerabilities in their dependencies. There are several important things to check before using certain libraries and packages:

  • Check that the package was recently updated
  • Use the latest versions of all NPM packages
  • Try to use packages with multiple maintainers to reduce the risk of abandonment
  • Check all packages for known vulnerabilities
  • Remove old unused packages as the code evolves over time
Frequently changing APIs

Frequent API changes are often stated to be one of the biggest drawbacks for Node.js developers. It’s worth noting that not all version updates and API changes are backwards compatible. Developers will have to make relevant code changes with each new version release.

Poor documentation for tools and packages

Node.js is known for having less-than-ideal documentation, leading to developers having to spend more time on understanding how and why specific solutions worked – or failed to work. When combined with Node.jss lack of a conventional approach (unopinionated frameworks) to building and scaling applications, each Node.js project will likely require and individual, unique, and internal process and set of best practices.

Who use Node.js?

Node.js is actively and extensively used with real-world applications – many of which you might use on a daily basis. We often hear how Node.js works well in high-speed, real-time web applications – but what are they? Is Node.js only used on smaller projects or on a massive scale by industry leaders? Here we explore some real examples of how and where Node.js is used today! Let’s take a look.


Previously built with Java backend, Netflix had great data management, but offered comparatively poor user waiting times. One of Netflix’s goals was to improve user site loading speeds – and this is where Node.js was effectively introduced.

Moving over to Node.js enabled Netflix to streamline communication between the frontend and backend; whereas previously the transition between frontend and backend wasn’t as smooth, which led to higher load times and increased latency at the end-user level.

3 ways Netflix benefited from using Node.js:

  • 70% net reduction in its interface startup time (from 5-10 seconds down to just 1 second). 
  • 30-minute plus Java startup time brought down to just one minute.
  • Efficient and improved scalability as Netflix’s userbase rapidly grew.


LinkedIn’s app was built with Ruby on Rails. Its growing user base would have meant sinking huge resources into hardware expansion – without necessarily solving the underlying software issues. LinkedIn’s choice to switch over to Node.js better suited processing multiple concurrent requests, particularly when user traffic increased. Today, LinkedIn is one of the largest apps that use Node.js on its backend.

How switching to Node.js helped LinkedIn:

  • Massively reduced the hardware resource requirements to host their app.
  • Made it easier for developers to manage and maintain frontend to backend interactions.
  • LinkedIn’s codebase became more modular and was simplified app-wide.


As one of the world’s largest domain name and hosting providers, GoDaddy places great importance on their server load and pricing. With the goals of reducing server load, bringing down prices, and improving the performance of their website builder tool, GoDaddy adopted Node.js back in 2016. Today, GoDaddy is one of the world’s largest Node.js backers.

How Node.js benefited GoDaddy:

  • Improved the performance of website hosting (for websites built with GoDaddy’s builder tool) for end-users.
  • Slashed costs significantly, making their hosting more accessible.
  • Launched their rebranded website in under 60-minutes, in which Node.js played an important role in enabling a smooth transition.

Frequently Asked Questions (FAQ)

Node.js is used to build fast and highly scalable web applications, backend API services, and real-time, push-based applications. Node.js’s non-blocking I/O, event-driven architecture lends well to handling multiple concurrent requests and data-intensive applications. Node.js also plays a key role in the MEAN, MERN, and MEVN full-stack JavaScript stacks.

Node.js is actively used by several large companies and organizations around the world, including popular brands such as Netflix, Trello, LinkedIn, GoDaddy, PayPal, Uber, and many more. Node.js has increased in popularity over the past several years and still stands as one of the most widely-used software development technologies.

Node.js is not a framework. Node.js is a runtime environment powered by Chrome’s V8 engine, allowing Node.js to execute JavaScript code outside of the browser. Node.js is the foundation for several widely used frameworks such as Express.js and Next.js.

Node.js is written in JavaScript, which is one of the most popular programming languages. Developers familiar with JavaScript and its syntax will find Node.js quite easy to pick up and get started with. The Node community is large and active, providing in-depth guides, best practices, solutions to common issues, and more. NPM (Node Package Manager) provides over 800,000 Node.js code packages – so you don’t have to manually write every line of code.

Node.js can be used to build both frontend and backend web applications using JavaScript. Previously, you’d have to build the frontend and backend with different programming languages, frequently switching between contexts, etc. It’s a common misconception that Node.js is a backend-only technology – even though it’s more commonly used to build backend API services, web applications, and web servers.