Hire Top Freelance Node.js developers with Ultragenius

Ultragenius is a marketplace for top software developers, engineers, programmers, coders, architects, and consultants. Top start-ups and companies choose developers from Ultragenius platform for their critical software projects. Hire from Ultragenius network & scale your engineering team in a matter of few days. 

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Node.js Developer

Rishabh is a software engineer having 7+ years of experience in designing back-end web applications using Node.js.

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10 Years


Full Time


NodeJS Freelancer

Mahesh is a software engineer having 3+ years of experience in developing server-side applications with Node.js.

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10 Years


Full Time


Part-time NodeJS Freelancer

John is a software engineer having 10+ years of experience working with Node.js, ExpressJS, and Cassandra.

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Hire top freelance NodeJS developers with Ultragenius

NodeJS is a Javascript backend runtime environment built on the Chrome V8 engine and executes Javascript code independent of the web browser. Node.js is mainly used for non-blocking Input/Output programming. Its single-threaded nature makes it very fast for developing web applications. It is used for backend services and generating dynamic content on the webpage. NodeJS can gather form data and perform CRUD ( Create, Read, Update, and Delete ) operations and easily modifies data in your database. 

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Developers' Reviews for Ultragenius

Ultragenius offers a great opportunity to work in mission-driven U.S. companies with a great salary. I am glad that I chose Ultragenius to find my dream job.
Jason Martin
Freelance Node.js Developer
Once you are part of Ultragenius, you don't have to look for another platform which leads you to your dream job. Ultragenius's vetting tests and assessments are unmatchable and helped me a land an excellent job.
Barbara Smith
Freelance Node.js Developer
I will thank to Ultragenius wholeheartedly. It helped me securing a career-growing high paid job which I couldn't think would be possible for me without this top connecting network.
Mark Sommers
Senior Node.js Developer

Join 200+ Fast-scaling Start ups
and Fortune 500 Companies that have hired freelance NodeJS developers

Want to hire freelance Node.js developers on your own? Here are the skills you must look for while hiring a Node.js developer

Hiring freelance Node.js developers can be a complex task for you if you are a non-technical manager. Javascript is the core skill of any developer without which no framework and related skills can be mastered and hiring the top skilled freelance Node.js developer among the thousands of developers will be challenging to you even if you belong to technical background. But, no worries, Ultragenius is here to assist you in hiring only the top 1% freelance Node.js developers.

These skills you must ensure in any freelance Node.js developer – 


Strong knowledge of core Node.js modules -
Node.js modules are the folder containing multiple files, that are imported using require() method. The developer must possess strong knowledge of – 
  • HTTP
HTTP is a built-in package for designing client-server architecture and is designed to support various protocol features. ExpressJS framework uses HTTP to make the server request. 
  • File System
This Node.js module of the file system help developer to work with the file system of your computer and is used to read the files, write the files, rename the files, update the files, and delete the files.  E.g. var fs = require(‘fs’);
fs.readFile(“file.txt”, “utf8”, function(err, content) {
if (err) {
     return console.log(err);
  • Buffer
Buffer provides a way of handling data. It is a global object in Node.js and uses many methods like alloc(), allocUnsafe(), allocUnsafeSlow(), byteLength(), compare(), concat(), copy(), entries(), fill(), equals(), includes(), indexOf(), from(), isBuffer(), and many more.
  • Globals
Node.js has objects that are available in all the modules in NodeJS and can be directly used while developing a web application without importing them.
  • URL
The URL module resolves a web address that is readable. To include the URL module, add var URL = require( ‘ url ‘);
Strong knowledge of HTML5 and CSS3
HTML (Hypertext Markup Language) and CSS (Cascading Style Sheets) are the two core technologies to design a web page,  the most used versions are HTML5 and CSS3. You must hire such a developer who has practiced and worked deeply with these technologies. Knowledge of Flexbox and CSS Grid, in addition to Bootstrap, Semantic and Structural Styling, and Foundation is a must to a Javascript developer. Along with this, the developer should be well-versed in Javascript libraries especially jQuery and CSS grid systems. 
Proficient in using NPM and third party integration

A CSS pre-processor is a program that extends the functionality of CSS and compiles it

Next to NodeJS, the developer must know about Node Package Manager (NPM), how to use this tool for working with web applications on the backend side. NPM is the package manager for handling several server-side dependencies. NPM facilitates the developer by installing the Javascript libraries an application needs for development, testing, and production.

The developer must know the following commands –

  • npm install
  • npm init
  • npm start
  • npm ls
  • npm version
  • npm uninstall
  • npm update
  • npm update -g
  • npm doctor
  • npm deprecate
  • npm outdated
  • npm search
  • npm help
  • npm owner
Experience working with Node.js frameworks

For developing a web application in Node.js, its frameworks offer unique design patterns. Examples are Express.js, Meteor.js, Total.js, and Nest.js, being on the top is Express.js.

Express.js matches its pace with the high-speed input/output operations and aligns with the single-threaded node.js environment because it uses the concept of asynchronous programming where multiple operations are executed independently of each other. Express provides a robust application user interface (API) for client-to-server requests and interactive user applications. 

Meteor.js is another popular cross-platform framework of Node.js known for rapid prototyping with Command Line Interface (CLI) and making smooth data flow between the client-side and the server-side in any application where high-performance real-time functionalities are required. Developers can even deploy live updates on the already installed applications without interfering with the current ongoing session. 

Socket.io is also known for its real-time updating of responses and requests. It acts as bi-directional communication support for clients and servers. An example of this is Zoom, which needs communication of real-time bidirectional data to various participants and Socket.io makes it possible only with fewer lines of code.

Experienced in working with Version Control System (VCS)
Developers must have a very good knowledge of version control systems, like Git, SVN, TFS, and Mercurial. Mostly, developers use Git for their work. It is the version control system that helps the team in collaborating and organizing your code, maintain the frequent changes that occur in the code. Git helps in reviewing the old codes and compares them with the newly updated code, pulling the code from their repository, and managing the commit history.

Along with this, the developer must know how to use add, push, pull, and commit commands, branching, and merging as it allows developers to work independently on the code.
Excellent understanding of testing frameworks and tools

Rising quick-deployment needs during the development phase, testing has become an  important skill for Javascript developers. Therefore, developers should know about Jest, Enzyme, Mocha, Chai, AVA, and Tape for unit testing.

For end-to-end testing, they must know about Selenium, Webdriver, Cucumber.js, Nightwatch.js, Cypress, and Puppeteer.

For integration testing, they must know about Karma.

Strong grasp of Asynchronous Programming in Node.js

Asynchronous programming allows any program to serve multiple requests without blocking the execution of its previous request. All of the I/O functions in NodeJS  I/O are non-blocking and accept callback functions. If the developer wants to download any file, then the Node.js server will put this downloading job in the background without stopping the current flow of any process.

E.g .

var fs = require(‘fs’);
var fcontent ;
function readingfile(callback){
fs.readFile(“readme.txt”, “utf8”, function(err, content) {
 if (err){
 return console.error(err.stack);





function mycontent() {




console.log(‘Reading files….’);


Firm understanding of the databases like MongoDB, MySQL, and PostgreSQL
For developing real-world web applications, the developer should be experienced with at least one of the databases, MongoDB, MySQL, and PostgreSQL. These databases can store the content in any type of format and are frequently used with NodeJS.  To work with MongoDB, the required library is mongoose and for working with MySQL, the required library is mysql. The necessary operations to perform with these modules are – 
  • Connection Pooling – Specify the number of database connections that should be maintained and saved by Node.js.
  • Create the connection to a database. Create a callback function that can be invoked whenever the “create” method is executed.
  • To retrieve and manipulate data, execute queries from the database with the help of commands such as SELECT, UPDATE, INSERT, and DELETE.
  • Close the connection and create a callback function that can be invoked whenever the “close” method is executed.
Ability to write Cross-Browser compatible code

You must hire developers who can write the code that is compatible to run on any browser platform like Mozilla, Chrome, Internet Explorer. NodeJS supports cross-browser compatibility to its web applications and uses NightwatchJS for testing cross-browser applications.

Proficient Knowledge working with REST (Representational State Transfer) API (s) ​
REST API is an Application Programming Interface that uses HTTP requests to GET, PUT, POST, DELETE the data over www. The developers you are hiring should be well versed with the principles of REST – 
  • Stateless – 
The client sends the requests to the server containing all the necessary data to be dealt with. The data can be a query-string parameter, a part of URI, context body, and headers also. The URI uniquely identifies the resource and the body contains the information about the requesting resource’s state.
  • Client and Server – 
REST provides a uniform interface that separates the client from the server and helps in improving the UI portability across various platforms they use. It also increases the scalability of the server components.
  • Uniform Interface
REST API ensures uniformity throughout the application by defining four interface constraints –  Resource Identification, Resource Manipulation, Self-descriptive messages, Hypermedia.
  • Layered System 
REST provides a layered system architecture that limits the component behavior thereby ensuring stability. Layered system enables load balancing and enhances scalability by providing shared caches. It also helps in increasing the application’s security because components in each layer cannot communicate with the next immediate layer.
  • Cacheable
REST allows the client to download the applets and extend them via the interface to use in their applications.
Error handling skills

While hiring, ensure the developer’s knowledge on when to crash when to log an error, when to retry, and when to continue with the application. Examples you can ask about Troubleshooting and Syntax Manipulation are the main error-handling skills that every NodeJS developer should know. 

Proficient in writing optimized and readable code

You must hire the developers based on their ability to write clean and optimized code that is understandable by all the team members, and is scalable.

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Connect with the top 1% freelance Node.js developers of the world at the lowest prices

Developers use NodeJS to develop their web applications  because of its flexibility on both client-side and server-side and enriched Node Package Manager (NPM) which provides various libraries and packages to work with.  But recruiting the best freelance NodeJS developers is not an easy task where a large no. of NodeJS developers are competing to grab the job opportunities.

Top Interview Questions to ask while hiring a freelance NodeJS developer

Javascript is loosely or dynamically typed language. In loosely typed language, the data type of the variable is checked at run-time unlike strongly typed language where the data type of the variable is checked at the compile-time only. Variables in Javascript don’t hold any fixed data type. A variable assigned a string type can be converted into a string type and vice versa. For example var str = “Hello World !!!”, var str = 12345.

  1. Extremely fast for developing web applications
  2. Handle scalability problems
  3. Provides community support to solve the development problems
  4. Easier to learn and takes less time to write code.
  5. Helps in building cross-function team where a team has representatives from various departments like System Analysts, Developers, and Testers.
  6. Employs fewer resources and boosts application performance. 
  7. Easily extended and customized for rapidly growing enterprises.
  8. Developers can access several tools from Google Chrome Developer Tools which makes write and debug code easy for them and build cross-platform web applications. 

Asynchronous programming is a programming paradigm in which one part of the code runs without interrupting the main program flow. Asynchronous paradigm enables Node to accept multiple I/O operations without stopping code execution, that is why it is called non-blocking I/O.

For example, consider the file_system.readFile model synchronously and asynchronously.

  • Synchonous File Reading

var file_sys = require (‘fs’); var content = file_sys.readFileSync(“readme.txt”, “utf8”);


console.log(‘Reading file…’);

Here, file_sys.readFileSync() is the synchronized version of the file_sys.readFile();


  • Asynchronous File Reading

File var file_sys = require(‘fs’); 

file_sys.readFile(“readme.txt”, “utf8”, function (err,content){


return console.log(err);



console.log(‘Reading file…’);

In synchronous file reading, the code block will read the entire code and store it in the memory, and then go to print the data and the message on the console. Everything is discontinued until reading the file is finished. However,

In asynchronous file reading, the system is ready to invoke callback() function even while reading the file.

The output is first it prints Reading file… and then prints file content.

A callback function is passed inside another function as an argument and then gets executed inside another function. Callbacks do not execute the file procedurally, instead, they act asynchronously, e.g. when you try to download a file and you don’t want the server to block other jobs it is holding, rather send a download job in the background and invoke a callback function when it is finished downloading. This is an asynchronous paradigm server that is accepting requests while performing tasks currently.


  • A stub is a small program routine that replaces the longer program that is being tested and acts as a substitute for it. When the stub is wrapped in a function, the original function is not invoked, instead, a stub designed for that is tested first. 
    In other words, stubs are the dummy objects used in testing scenarios like -
  • In a piece of code, what happens if an error is thrown or if it passes the test cases.
  • External calls cause the test to run slow and difficult to write. 

The event loop provides support for performing non-blocking asynchronous I/O, in spite of Javascript being single-threaded. The event loop is a semi-infinite loop and exits at a point where there is no more work remaining to perform. Libuv, which is a cross-platform C library provides event loops.

The worker thread is a continuous parallel thread responsible for handling CPU-intensive Javascript operations by sharing SharedArrayBuffer instances or by transferring ArrayBuffer instances. Unlike cluster or child_process, worker threads can share memory. Worker threads inherit the command line flags automatically from the running process and will preload the preload scripts same as the main thread. If the preload script launches a worker thread unconditionally, every thread that is newly created or technically 'spawned' will spawn another until the application crashes.

Node Package Manager (NPM) is the CLI tool used for installing, updating, and uninstalling any node.js package in your application. Some of the important npm commands - 
  • For installing package.json - npm install
  • For installing  - npm i <package>
  • For uninstalling  - npm un <package>
  • For update - npm up <package>
  • List globally installed packages - npm list -g --depth=0
  • Uninstall global package - npm -g uninstall <name>
  • Upgrade npm on windows - npm-windows-upgrade
  • Update global packages - npm outdated -g --depth=0 , npm update -g <package> <package> <package>
  • Update npm - nvm install-latest-npm.
  • Set a default version of node - nvm alias default <node_version>

Hire freelance Ultragenius Developers based on skills


Frequently Asked Questions

Ultragenius is one of the leading platforms for hiring remote talent and connecting freelance and part-time developers with Silicon Valley businesses. We focus on finding the best talents who will perform extremely well and will be easily integrated into your teams. We filter out only the top 1% most skilled freelance developers among the 20K+ developers who have applied on our platform. Candidates have to prove their self-reported experience by giving Ultragenius’ s skill tests.

Ultragenius first tests the developer’s skill set by conducting a two and half hour hiring test. Our hiring test judges a candidate on all aspects like aptitude, case study analysis, verbal and reasoning, coding questions based on data structures and algorithms, software engineering, system design, and more. Then, there is another round for the candidates who are selected from this round called “Higher-level Assessment Skill Test”, which is a video round that deeply analyzes freelance developers’ major skills and asks questions about the projects they have worked upon.

Fill up the form which is on every hiring freelancers’ page and we will inform you once we select the top 1% freelance Node,js developers matching your job requirements.  After analyzing the candidates based on their resumes and two assessment tests, we provide you the feedback quickly. And if the freelancers selected by our team are fit for your job role, then we also provide the onboarding.


Ultragenius offers you only the most skilled freelance developers who are top 1% among the 20K+ freelance developers who have applied on our platform. After a rigorous selection and testing process, we sort out only the top candidates for you. You can check out Ultragenius’ s selection process for hiring freelance Node.js developers on http://www.ultragenius.club/hire-node-freelancer.


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