• Origin story: Earlier, a programmer was responsible for both, the frontend and backend set of operations. It was after Randy Schmid introduced full-stack development in 2008 that the two different streams of development came into the picture, the frontend and backend development.
• Widely popular: According to Free Code Camp, backend developers make up 12.2% of developers as compared to frontend developers that hold 5.8%. Full-stack developers have the highest count: 28%.
• Top languages used for backend development: According to Web directions, the most used backend programming language is PHP(64%), followed by Python(15%), Ruby(14%), and Java(12%).

• Facilitates information exchange: Backend development consists of code that’s not visible to the users. This code is responsible for storing, validating and passing data stored in the backend to the client front. In simpler words, it adds utility to each frontend functionality.
• Runs in various environments: Nowadays, businesses deploy their websites and web apps in different environments. Some choose to implement it on the server while some want cloud. Some combine both to increase scalability and performance. Backend development takes care of hosting websites in different environments.

The following are tools commonly used by backend developers to build and deeply code. While each language would have specialized tools, these find uses across languages.

1. Version control tools

These tools track and log the changes made to a system. Version control is done via Git repositories which track all the changes made to a particular file and saves them in a repository. This helps streamline the development process.

Tools used for version control include:

• GitHub - GitHub is a repo that lets you host Git projects. Teams can collaborate and view the entire code changes history.
• GitLab - This has a lot of useful features including Continuous Integration through which you can test and deliver your code files.

2. IDE/Code Editor

IDEs or Integrated Development Environments consist of all the basic tools needed to write and test the code developers write.

Some of the most popular IDEs are:

• a) Visual Studio Code - equipped with a broad array of dev tools which makes it easy to write, navigate and fix code files fast
• b) Atom - free and open-source text editor developed by GitHub, great for early as well as veteran users.

3. Issue tracking

These tools record incoming cases and requests and monitor their state from start to end. Jira and Trello are some commonly used issue tracking tools.

4. API platforms

API platforms are used by backend developers to build, share and test their APIs. Postman, Testfully, and Insomnia are well-known names among API platforms.

5. PaaS

Cloud Platforms as a Service are used by backend developers to work entirely on the cloud - from development to deployment. Some popular tools in this category are Heroku and Digital Ocean.

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 Backend 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.
• Expertise in a specific language: All languages have their peculiarities and nuances. While good backend developers can pick up other languages, it’s a plus point to hire a developer who already has expertise in it.
• 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: Hiring someone who has worked remotely in the past is an added advantage as they have front-hand experience of everything right from how the contracts work to communication and from timelines to 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

You can check out a more detailed backend developer job description here.

Now that you have made a quality JD, it can still be tricky to evaluate the skills of your applicants when you hire Backend developers. To help you with that, we have created a pool of questions that a good Backend 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. You can check out some related interview questions on these pages: MySQL, Rest API

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. This section 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

A session is used to establish and maintain the connection between the application and the database. Sessions are designed to be lightweight and only instantiated whenever data is required from the database.

Session objects are not thread-safe and hence it is not a good practice to have them always opened. Additionally, Session can be used to retrieve, store or delete data from the database.

What is YAML in Spring Boot? Why is it used?

Spring boot YAML can also be used to define properties and is an alternative to the application.properties file. Whenever the SnakeYAML library is in your classpath, the SpringApplication class automatically supports YAML as an alternative to properties.

B. Advanced concepts

What are the different types of classes in C#?

Classes are used widely while working with C#. It comes with 4 different types of classes. 

• Static Class: Static classes contain static members, methods, and constructors. Static classes do not allow new objects to be created. Static classes are sealed, hence you cannot inherit a static class from another class.
• Partial Class: A partial class allows users to split the functionality of a class across the same file or even multiple files. During compilation, all instances are combined and treated as one. Partial classes are defined using the partial keyword. Splitting a class allows multiple developers to work with the same class simultaneously. However, keep in mind that if any instance of the class is declared sealed, abstract, or base, the whole class is declared with the same type.
• Abstract Class: Abstract classes are restricted classes that cannot be used to create objects. However, an abstract class must contain at least one abstract method. These methods do not have a body and are declared inside the class only. The abstract keyword is used to define an abstract class. The purpose of an abstract class is to provide a blueprint for derived classes and set some rules on what the derived classes must implement when they inherit an abstract class.
• Sealed Class: Sealed classes restrict users from using inheritance, preventing the user from inheriting another class from it. Sealed classes are defined using the sealed keyword. Given the inheritance attribute has been taken away, sealed classes work best when used with a class inheriting static members. 

What does the forEach() method in Java do? Explain with an example.

forEach() is a method that is used to iterate over objects in Java. However, unlike other loops, a loop counter is not declared or initialized but rather a variable is passed as an iterable.

Hence, forEach() is commonly used with arrays or collection classes.

Syntax

   for (type var : array) 
{ 
    statements using var;
}

Example Using forEach():

 class ExampleForEach   
{
    public static void main(String[] arg)
    {
        {
            int[] scores = { 10, 13, 9, 11, 11};
            
            int highest_score = maximum(scores);
            System.out.println(highest_scores);
        }
    }
    public static int maximum(int[] numbers)
    {
        int max = numbers[0];
        
        // for each loop
        for (int n : numbers)
        {
            if (n > max)
            {
                max = n;
            }
        }
    return max;
    }
}

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 ValidParenthesesFunc {
    func isValid(_ s: String) -> Bool {
        var stc = [Character]()

        for char in s {
            if char == "(" || char == "[" || char == "{" {
                stc.append(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.  Write a program to find whether a string or number is palindrome or not.

function palindrome(myString){
    var removeChar = myString.replace(/[^A-Z0-9]/ig, "").toLowerCase();
    var checkPalindrome = removeChar.split('').reverse().join('');
        if(removeChar === checkPalindrome){
          document.write("<div>"+ myString + " is a Palindrome<div>");
        }else{
          document.write("<div>" + myString + " is not a Palindrome <div>");
        }
}
palindrome('"Oh who was it I saw, oh who?"')
palindrome('"Madam"')
palindrome('"Star Wars"')
palindrome('"7,10,7,8,9"')

The output of the above code will be: 

"Oh who was it I saw, oh who?" is a Palindrome
"Madam" is a Palindrome
"Star Wars" is not a Palindrome.
"7,10,7,8,9" is not a Palindrome.

3. What will the output of the following code be?

var x = 10;
var y = 5;
var z = 3;
if (x / y / z)
     document.write("hi");
else
    document.write("hello");

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

The answer is A, the floating-point division in JS returns a non zero value = 0.66 which evaluates to 
true and outputs ‘hi’.

That is everything you need to know about hiring a freelance Backend developer. As discussed, it isn't easy to find a quality freelance Backend 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 Backend 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.

That is everything you need to know if you want to hire Backend developers. Happy hiring! :)