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Senior NodeJS Developer


DXC Tech
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Senior NodeJS Developer


Navori Labs
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Senior NodeJS Developer


Teller Finance
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NodeJS Developer


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Senior NodeJS Developer


Pecan Analytics
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Top NodeJS Developers are Handpicked by Flexiple


    Surbhi has 4+ years of experience in software development and has worked as a Full Stack developer with experience in building apps across NodeJS, ReactJS, ... Surbhi has 4+ years of experience in software development and has worked as a Full Stack developer with experience in building apps across NodeJS, ReactJS, and AngularJS. She has been working on remote contracts for the past couple of years as a freelance NodeJS developer and possess good communications skills (verbal and written) and is very responsive. Read MoreRead Less

    Worked at DXC Tech

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    Eric, a freelance NodeJS developer has a prolific record of building multiple large-scale web applications. Having been freelancing for the past 4 years, he has ... Eric, a freelance NodeJS developer has a prolific record of building multiple large-scale web applications. Having been freelancing for the past 4 years, he has worked for various startups in roles that range from Junior to Lead Developer. He is also an accomplished blogger with several published tech articles under his belt. Read MoreRead Less

    Worked at Navori Labs

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    A seasoned and versatile professional with over 10+ years of experience in the software industry, Bala has an entrepreneurial mindset with meticulous attention to detail ... A seasoned and versatile professional with over 10+ years of experience in the software industry, Bala has an entrepreneurial mindset with meticulous attention to detail and the ability to decouple and re-engineer existing applications. He is an avid programmer with a flair for technical management and aptitude to learn new technologies. Also, over more than 6+ years, Bala has worked as a freelance developer on NodeJS, Angular, AWS and PHP, etc. Read MoreRead Less

    Worked at Infosys

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    Ravish is a polyglot developer with 15+ years of experience. Over his career, he has worked on modern software development technologies such as JavaScript (NodeJS, ... Ravish is a polyglot developer with 15+ years of experience. Over his career, he has worked on modern software development technologies such as JavaScript (NodeJS, ReactJS, React Native) building complex applications for the likes of IBM and Amazon. Since June '19, he has been enjoying the freedom that goes along with being a freelance NodeJS developer and enjoys teaching coding in his free time. Read MoreRead Less

    Worked at Mobiquity

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    Tri is a Full Stack Developer, who specializes in developing web applications for data analytics. His top skills include NodeJs, ReactJS, Python, AWS, Kubernetes and ... Tri is a Full Stack Developer, who specializes in developing web applications for data analytics. His top skills include NodeJs, ReactJS, Python, AWS, Kubernetes and he started his career as an intern at Google while picking up Django. He has worked in many product-based companies and has built a knack for developing complex and interactive applications. He then started freelancing as a developer on technologies including NodeJS, Python, etc. from 2018 and is excelling in working on challenging projects including ETL/ ML projects. Read MoreRead Less

    Worked at Pecan Analytics

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    Rex, an experienced software consultant, has a demonstrated history of working in the computer software industry. With 15+ years of experience, Rex, also a freelance ... Rex, an experienced software consultant, has a demonstrated history of working in the computer software industry. With 15+ years of experience, Rex, also a freelance NodeJS developer, has a diverse portfolio which includes projects in various companies as well as independent projects. Rex is well versed with Backend Design and Development, Database Design and Programming, API Design and Development, Mobile Application Development, PHP MVC Framework and Javascript Cloud Server Management among others. Read MoreRead Less

    Worked at Honeycomb

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    Komal is a software engineer with 5+ years of experience in developing scalable and concurrent business applications. Further, being exposed to the agile methodology gives ... Komal is a software engineer with 5+ years of experience in developing scalable and concurrent business applications. Further, being exposed to the agile methodology gives her the ability to adapt to new technologies, learn, master and coach. She has also gained experience as a freelance developer and has worked on NodeJS, ReactJS, AngularJS and Java. Read MoreRead Less

    Worked at Thoughtworks

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    NodeJS Java ReactJS

    Archibold is a full stack developer with 4 years of overall experience. He is a developer who can develop both web and mobile applications where ... Archibold is a full stack developer with 4 years of overall experience. He is a developer who can develop both web and mobile applications where TickethouseGh is one such project. He is an expert in technologies like NodeJS, ReactJS, Java, Kotlin, Android, etc. He is capable of building applications from scratch as a sole developer and as a team member as well. Read MoreRead Less

    Worked at Rancard

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Frequently Asked Questions

  • How To Find The Best NodeJS Developers For Hire?

  • NodeJS is a server-side platform built on Google Chrome's JavaScript Engine (V8 Engine) written by Ryan Dahl in 2009, about thirteen years after the introduction of the first server-side JavaScript environment. According to SimilarTech, there are about 165 thousand websites build using NodeJS, with the United States having the highest share.

    If you’re looking to hire NodeJS developers, this guide is going to help you find the perfect fit. We’ve included everything you need to know about hiring a great freelancer for your company.

    Before diving into the fundamentals of hiring a freelance NodeJS developer, let's delve into some interesting facts about the history of NodeJS.

    1. Let's introduce NodeJS to you

    • Origin story: With the emergence of JavaScript and PHP, developers began to push their limits with web apps, but the browsers back then couldn’t keep up. So, Google launched Chrome. The team chose to build the actual JavaScript interpreter as a stand-alone project and called it JavaScript engine “V8”. V8 was amazingly fast, which gave Ryan Dahl the brilliant idea of using V8 on the server-side to execute JavaScript on the server, which let to NodeJS.
    • Widely popular: The United States has the most number of websites developed using NodeJS (37K+), followed by Russia(11K+) and China(10K+).
    • Used by top companies: Top companies like Netflix, LinkedIn, Wallmart, Trello, Uber, Medium, eBay, etc. use NodeJS.
    • Other trivia: The initial release of NodeJS only supported Linux and Mac OS X.
    • 2. Why is NodeJS widespread?

      • Performance and Scalability: NodeJS being built on V8 operates on a single thread, making use of the event loop and callbacks for I/O operations, thus handling hundreds of thousands or even a million concurrent connections.
      • NPM(Node Package Manager): Gives developers multiple tools and modules to use, thus further boosting their productivity.

      3. What are the tools used by NodeJS developers?

      Here are some of the top tools that NodeJS developers use to build applications:

      1. WebStorm

      WebStorm is an Integrated Development IDE created by JetBrains. It works very well with JavaScript and is hence used extensively by NodeJS developers. The platform is lightweight and equipped with all the components needed for NodeJS development on the frontend and backend.

      2. npm

      npm or Node Package Manager includes a command-line client and an online registry. It is the default package manager when using NodeJS. The use of NPM sorts modules and aids in the publishing, installing, and managing of NodeJS software. NPM registry has thousands of code packages that can be used by developers.

      3. Webpack

      Webpack serves as a module bundler. Mainly, it puts together JS files to be used in a browser. It combines a large number of files into a few files necessary to run the app.

      4. PM2

      A process manager for NodeJS apps, PM2 is easy to use and comes with many in-built features. This tool monitors an application in real-time and gets it up and running without you needing to worry about restarting it.

      5. Babel

      This tool is a JavaScript compiler. The use of Babel allows for easy compilation of ES6 or ES7 to ES5 for use in the production of the app. In the transfer of the code from the new to the older version of ES, Babel also tries to make use of a minimal number of lines of code.

      6. Electrode

      An open-source platform for React/NodeJS, Electrode enables building NodeJS apps in a well-structured way. It makes writing core NodeJS code easy as well as provides some complex modules to add advanced features. Thanks to Electrode, NodeJS developers can reuse code and optimize and deploy software with ease.

      4. Writing the job description to hire NodeJS developers

      Below are some key points that we at Flexiple have learned through trial and error - a process of filtering through over 15,000 developers. You can use these in your process to hire NodeJS developers.

      • Years of software development experience: Be specific about the technology you’re looking for and the number of years of experience needed. A proxy to years of experience can be the number of production-level apps worked on.
      • Type of products built in the past: Based on the type of product you are trying to build - social network, SAAS product, etc. - you can prioritize certain developers over others.
      • Exposure to specific industries: Developers who have built products in certain industries will already know key aspects of laying the foundation for a great product and will be able to predict possible problems.
      • Experience working remotely: A developer with past remote work experience is an added advantage as they would have first-hand experience of everything - right from how contracts work to streamlined communication, as well as timelines and deliverables.
      • Strong communication: An essential thing to look at when hiring a freelancer is excellent communication skills. Since all the interaction happens online, a freelancer should be able to effectively communicate to ensure a streamlined execution of all work.
      • 5. Interview Questions to hire NodeJS developers

        Now that you have made a quality JD, it can still be tricky to evaluate the skills of your applicants when you hire NodeJS developers. To help you with that aspect of hiring a NodeJS developer, we have created a pool of questions that a good NodeJS developer should be comfortable with.

        It is important to note that the ability to answer these questions doesn't imply that you have a top quality candidate. But it definitely is a big step in that direction.

        To help you navigate through these questions, we’ve categorized the interview questions in 3 parts:

        A. Basic concepts: Includes all basic concepts used across languages but we've focused on their significance in NodeJS. This will give you an understanding of how strong their programming foundation is.

        B. Advanced concepts: Includes all concepts that someone with higher expertise should know.

        C. DS/Algorithm questions: To test the logical capability of the candidate.

        A. Basic concepts

  • How is NodeJS asynchronous when javascript is single-threaded ?

    We first need to understand that NodeJS is just a Javascript runtime built on Chrome’s V8 engine. The V8 engine was originally made by Google for Google. It was written in C++ to compile Javascript functions to machine code. It is highly efficient and optimised and is also used in Google Chrome for the same purpose.

    Javascript is a single threaded language. This means that it has one call stack and one memory heap. Due to this it has to execute code sequentially. But as we know, the devils of synchronous programming can often decrease the efficiency of code. This is primarily due to blocking code which takes a long time to execute, such as I/O operations.

    Request Handling in Browsers

    To combat this problem, we have the different browser engines such as Chrome’s V8 engine, Firefox’s Spidermonkey, etc.. Tasks which take a long time are handled by Web API of these engines, which handle them in the background and allow synchronous execution of the rest of the code. When the background task in the Web API is done, a callback is pushed to the call stack.

    Multi-threaded Request-Response Architecture

    In other popular web application technologies such as JSP, Spring, ASP.NET, the language spawns a thread for each request and the thread executes the request and sends back a response. This is known as Multi-threaded Request-Response architecture.

    Single-threaded Event Loop Architecture

    NodeJS on the other hand follows a path similar to Javascript. NodeJS follows Single-threaded Event Loop architecture. It is built upon Javascript’s event based model with its callback mechanism.

    The NodeJS web server internally maintains a thread pool to handle client requests, but these are not meant to be handled and used by the developer directly. The number of threads in the thread pool depends on the number of cores the CPU has. When the web server receives the requests, they are added to a queue known as ‘Event Queue’.

    ‘Event Loop’ is yet another internal component which is central to this architecture of NodeJS. Event Loop uses a single thread only. It runs indefinitely and checks the Event Queue for requests. If the request does not require any blocking I/O operation like handling file system, database, then the single thread directly executes them. But if there is any such operation then a thread is picked up from the thread pool, assigned to the request, and when it finishes puts a callback in the Event Loop.

    Therefore, NodeJS runs on a single thread, similar to Javascript, but it maintains a thread pool from which it spawns threads to run asynchronous functions in the background.

    B. Advanced concepts

  • As NodeJS is asynchronous how do you manage when you need to make sequential requests, that is one request that depends on the previous one?

    Synchronous programming means sequential execution of code. That is, the next block of code executes only after the first block of code.





    As you can see each console.log() executes one after another.

    Asynchronous programming means the code doesn’t run in the sequence that it is written in. In this, the code executor doesn’t wait for the task to finish before proceeding to the next task. Hence, synchronous functions are often called “blocking” as they block further code execution and asynchronous functions are called “non-blocking”.


    setTimeout(() => console.log(2), 0)



    According to sequence, the 2nd console.log() should have fired before the 3rd one, but as setTimeout is an async (asynchronous) function it allowed the code to move on and the 3rd line was executed before the 2nd one.

    Now, some logic needs to be executed sequentially. For example, fetching records from a database, then editing it and finally updating the record in the database. This cannot be executed in an async manner because the order is important for this. Therefore, an async function uses callbacks, promises, or async-await to be able to sequentially work with such code.

    Callbacks were quite popular in the past, but also became infamous for ugly looking nesting called “callback hell” which made it difficult to maintain. So promises have become more popular. They function similar to callback - you attach a “.then()” at the end of the function and follow up with a catch block at the end which handles the errors.

    Example: - if fun() is our main function inside which promise() is an async function which is being called then it would look something like this:

    fun = () => {
      promise().then(() => {
        console.log("executed code")
        // sequential execution occurring after the promise function is executed
      }).catch((e) => {

    If the promise function returns something then it would look like this:

    fun = () => {
      promise().then((data) => {
        // sequential execution occurring after the promise function is executed
        // and data is what it returns
      }).catch((e) => {

    But the ugliness of callback hell nesting is avoided by doing promise chaining:

    fun = () => {
      promise().then(() => {
        return "first promise"
      }).then(() => {
        return "second promise" 
      }).then(() => {
        return "third promise"
      }).catch((e) => {

    Here each block of code is executed after the previous block of code.

    Async Await is a more refined form of promises. It is even referred to as syntactic sugar as the code looks much better after it:

    fun = async () => {
      const var1 = await promise()
      const var2 = await promise()
      const var3 = await promise()

    Async is a keyword which needs to be defined so that await can be used inside the scope of the function. Await causes the next lines of code to wait for the response from that function. This allows the code to look much better and we can actively decide whether we want the function to run asynchronously or synchronously.

  • What is a load balancer and how will you set it up?

    First let us discuss why load balancers are required. As the traffic increases on a server, the server experiences a slow down. To prevent this slow down, the server needs to be scaled up. Scaling of server can be achieved in two ways:

    1. Vertical Scaling
    2. Horizontal Scaling

    Vertical scaling refers to upgrading the resources of a particular server by increasing storage, increasing RAM, upgrading CPU. This gives the server more cores, faster execution speed, faster access time to storage and more storage. This was largely the traditional way of increasing performance of a server.

    Horizontal scaling refers to using multiple servers to increase the performance of the back end infrastructure. So, instead of boosting resources of one server, multiple servers are used together. This has been found to be cheaper than vertical scaling and therefore practiced on a large scale. A load balancer is, thus, required in case of horizontal scaling.

    In software development, load balancing refers to the process of distributing a set of tasks over a set of resources, with the aim of making their overall processing more efficient. Coming to backend development, load balancing refers to efficiently distributing incoming network traffic across a group of backend servers. Such a group of servers is called a server farm or server pool.

    Along with distributing traffic load balancers also help in preventing a server from becoming a single point of failure. In a large scale architecture load balancers can be placed at 3 levels:

    • between client and web server
    • between web server and internal platform layer (like cache server or application server)
    • between internal platform layer and database

    But we are primarily going to focus on the first one.


    One server is taken primarily for load balancing. The requests first hit this server and then based on the load balancing algorithm the request is routed to one of the several back end servers, which carry out the request.

    A load balancer considers two factors before forwarding a request:

    • An algorithm that helps in choosing from the healthy servers
    • If the server chosen is responding appropriately

    The different algorithms used by a load balancer are:

    1. Least Connection Method: Direct traffic to the server with fewest active connections
    2. Least Response Time Method: Direct traffic to the server with fewest active connections and least response time
    3. Least Bandwidth Method: Direct traffic to the server serving the least amount of traffic (measured in Mbps)
    4. Round Robin Method: Directs requests to servers in a cyclic manner
    5. Weighted Round Robin Method: Different servers are weighed according to their resources, accordingly the one with more weights is given more priority.
    6. IP Hash: A hash is calculated of the IP address of the client. The server to forward the request to is chosen based on the hash value. 


    A popular software used for load balancing is NGINX. It is an open source software for web serving, reverse proxying, caching, load balancing, media streaming, and more. It started out as a web server designed for maximum performance and stability. In addition to its HTTP server capabilities, NGINX can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy & load balancer for HTTP, TCP, and UDP servers.

    It is quite simple to use NGINX as a load balancer. Install NGINX in the server chosen to be as the load balancer.

    upstream app_servers {     
        server backend1.example.com; 
        server backend2.example.com; 
        server backend3.example.com; 
    server {
            listen       80;
            server_name  localhost;
    location / {
       proxy_set_header X-Real-IP $remote_addr;
       proxy_set_header Host      $http_host;
       proxy_pass       http://app_servers;

    The upstream app_server block holds the servers to redirect requests to. Inside the location block, we are setting app_server as the target block. The server_name identifies which domain the load balancer will show.

  • Give a detailed overview of any one authentication strategy?

    Web apps need to be authenticated to ensure that only the required people get access to the required data. Without strong authentication, you can suffer problems ranging from unauthorized login to complete leak of the database.

    Authentication strategies are methods for user authentication and management. There are multiple ways to achieve this. With a constantly shifting landscape, it is difficult to zero in on one strategy as the best. Yet, it is a necessary element of almost all real world NodeJS projects.

      The authentication strategies in NodeJS can broadly be classified into 3 types:
    • Middleware Modules (like Passport.js)
    • User Management as a Service
    • Custom Database and Authentication

    Middleware Modules

    These are npm packages such as Passport.js, Everyauth and Permit. These are packages that work on top of NodeJS frameworks such as Express.js, Koa.js, Hapify.js. They utilise the ‘connect’ middleware conventions. This means that while using the aforementioned frameworks, you can just plug in the modules and use their functionality.

    These mainly deal with session management, and also provide single sign on features. But their functionality is largely limited to this. They do not provide other features like account verification and password reset, which are left to the developer to develop.

    Passport.js is by far the most popular amongst these packages. It is an authentication middleware designed primarily to authenticate requests and to safeguard endpoints/routes from unknown users. It can be implemented within an Express-based NodeJS web application.

    Today, there are multiple ways of providing authentication: like a simple sign up/login or single-sign-on using an OAuth provider such as Facebook or Github, etc.. Passport offers a varied set of such mechanisms in the form of different packages, so that the developer doesn’t have to be burdened with extra dependencies.

    app.post('/login', passport.authenticate('local', { successRedirect: '/',
                                                        failureRedirect: '/login' }));  

    As you can see in this route, passport.authenticate() is a middleware in the Express app route. In the passport authentication, ‘local’ option is opted which means using a custom username and password instead of OAuth through Facebook, Twitter or any other such provider. If the authentication is successful, then the user is redirected to the route ‘/’ and if it fails then the user is redirected to ‘/login’.

    User Management as a Service

    These are services such as Stormpath/Okta, Keycloak and Auth0. Over time, software has moved from on-premise to the cloud, to now a distributed API service. These technologies provide Identity Management APIs for software teams building web, mobile and API driven applications.

    Identity management (ID management) is the organizational process for identifying, authenticating and authorizing individuals or groups of people to have access to applications, systems or networks by associating user rights and restrictions with established identities.

    Such pre-built authentication and user management cut down cost & security risk of developing and maintaining identity in house. As a result, developers can focus on the core features instead. Compared to middleware modules, these provide more features than just securing endpoints. This includes email account verification, password reset workflows, role-based access, two-factor authentication and so on.

    But introducing 3rd party services always has the requirement to be highly available, fast, portable, provide security during transport and most importantly provide flexibility based on the user model. These conditions vary vastly from service to service and an in-depth study needs to be done of all these before adopting a service.

    Stormpath is one such service that offers identity management APIs. It is a cloud-based user data storage system with an option for private deployment. Features include user registration, authentication, authorization, user profiles, single-sign-on, multi-tenancy, token authentication, and API key management. It has an open source SDK present for most popular languages like NodeJS, Angular, Java, PHP, Python, Ruby, .NET, iOS, Android.

    Stormpath also supports easy integration with Passport.js.

    var spClient = new stormpath.Client({ apiKey: apiKey });
      // Grab our app, then attempt to create this user's account.
      spClient.getApplication(process.env['STORMPATH_APP_HREF'], function(err, app) {
        if (err) throw err;
          givenName: 'John',
          surname: 'Smith',
          username: username,
          email: username,
          password: password,
        }, function (err, createdAccount) {
          if (err) {
            return res.render('register', { title: 'Register', error: err.userMessage });
          passport.authenticate('stormpath')(req, res, function () {
            return res.redirect('/dashboard');

    This showcases a part of how working with Stormpath would be for a developer. Here the createAccount() feature of Stormpath is being showcased. As you can see that Passport.js is also being used and the ‘stormpath’ strategy is chosen.

    Custom Database and Authentication

    This is the more do-it-yourself approach, where the developer builds the whole authentication architecture from scratch. It first starts with choosing your tech stack, database, hashing algorithm, method of maintaining sessions and so on. After this, the next part would be to build the user management service.

    It is a common task as it is intrinsic to almost any real world project. But it is prone to error - as anything built from scratch suffers from. Moreover, there is a hefty amount of code to be maintained too. But this strategy provides the most amount of flexibility and freedom to the developer.

    A traditional stack for achieving this would be to use a database like MongoDB or PostgresQL. Pick the required ORM like sequelize or mongoose with them. Bcrypt is a popular hashing algorithm which also has npm packages for its easy implementation.

    After this, routes need to be created for account creation, user verification, login and password reset. Thereon, an authentication logic is written to secure the different endpoints, and even the database needs to be secured from unauthorized access using secret keys.

    C. Data Structure/ Algorithm

  • 1. Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Note that an empty string is also considered valid.

    class ValidParentheses{
        func isValid(_ s: String) -> Bool {
            var stc = [Character]()
            for char in s {
                if char == "(" || char == "[" || char == "{" {
                } else if char == ")" {
                    guard stc.count != 0 && stc.removeLast() == "(" else {
                        return false
                } else if char == "]" {
                    guard stc.count != 0 && stc.removeLast() == "[" else {
                        return false
                } else if char == "}" {
                    guard stc.count != 0 && stc.removeLast() == "{" else {
                        return false
            return stc.isEmpty
    The above code will input 0(false). 
  • 2. What will the output of the following code be?

    var a = 10;
    var b = 5;
    var c = 3;
    if (a / b / c)

    a) hi
    b) hello
    c) error
    d) no output

    The answer is A because the floating-point division returns a non zero value = 0.66 which evaluates
    to true and outputs ‘hi’.
  • 3. What will the output of the following code be?

    var p = 2;
    var q = 4;
    var r = 6;
    if (p > q > r)
    The answer is False. It may look like the output can be true because 6 > 4 > 2 is true, but PHP evaluates $z > $y 
    first, which returns a boolean value of 1 or true. This value (true or 1) is compared to the 
    next integer in the chain, bool(1) > $z, which will result in NULL and echo “false.”

    Hire NodeJS developers - parting thoughts

    That is everything you need to know about hiring a freelance NodeJS developer. As discussed, it isn't easy to find a quality freelance NodeJS developer but this guide makes the process easier for you. To offload the entire hiring process, reach out to us at Flexiple. We've designed a high-quality, 6-step screening process to find the top 1%, freelance developers. You can find the best freelance NodeJS developers here. We've already served over a hundred clients, earning great reviews for the quality of service.

    Lastly, to quickly summarize it for you:

    • Note your project requirements and hire accordingly. Do not go for the lowest or the highest-paid developer.
    • Don’t hire without vetting- consider asking questions right from the basics to advanced to logical questions.
    • Look for companies like Flexiple that help you find the perfect fit.

    Happy hiring! :)

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