Backend developer interview questions and answers series- Part 1

The power source of the web is backend development. Therefore, apart from being exciting, backend development is also an innovative and empowering role. With advanced technologies, the demand for backend development has increased. 

In 2022, in the United States alone, the total population of web developers and digital interface designers was around 2,00,000. And this number is predicted to follow an upward curve in 2023, taking the total number to over 2,29,000. Without backend development, the ability to browse your favorite sites seamlessly won’t be a reality. Does the backend development domain excite you? Are you preparing to appear for a backend developer interview? Well, good thing we’re here to help you crack your tech interview!

Technical Questions for Backend Development

1. What are backend programming languages?

The backend architecture can be categorized into two broad segments: object-oriented programming and functional programming. 

Object-oriented programming 

• Object-oriented programming is a programming paradigm that focuses on creating and using objects for real-world modeling entities. 
• A key feature of object-oriented programming is the use of data encapsulation – an object’s internal state is kept in private fields, and its public interface consists of properties and methods. 
• Examples: Python, .NET, and Java.

Functional programming

• Functional programming languages are also known as declarative languages because they declare what operations should happen instead of how they should happen. 
• In these languages, functions generally take arguments (which may have default values) and return results without changing the global state or preserving side effects.
• Examples: Haskell, Ruby On Rails, SQL, Clojure, and Scala.

2. Explain the concept of APIs

APIs are a set of tools, standards, and programming languages that enable software developers to build applications that access data and services. An API is like a bridge between the two worlds of code and data. For example, if you want to develop a website that displays real-time stock quotes, you could use an API to connect your app with the stock market’s servers. The stock market would provide you with data about stocks (such as their names, prices, and descriptions), and then you’d use that information in your app. Developers typically leverage Python and NodeJS to create the APIs. 

3. What is your favorite programming language, and why?

I’ll give you my personal choice here. My favorite programming language is Python. I love it because it’s a functional programming language and offers a large library of functions for versatile backend development. It’s also easy to learn and fun to use, so you don’t get bored while you’re learning. There are other reasons I have an inclination toward Python programming:

• It’s not as difficult to write large projects with other languages because it has great libraries like NumPy and Pandas that make working with data easier.
• It’s not as difficult to read code because they’re usually written in English instead of cryptic coding language.
• It’s easy to find help online if you need it because there are so many resources out there!

4. Explain the difference between software architecture and software design

Software architecture is the technical structure of your product, while software design is the look and feel of a product. The two must work together to create a successful product for your customers. Software architecture deals with the internal workings of a system, while software design focuses on how it will interact with people and other systems.The most common distinction between software architecture and software design is in their respective roles: architecture describes what a system does, whereas design describes how it does it. Software architecture includes things like databases, user interfaces, and networking protocols. Software design includes everything from how buttons look on your web page to whether or not you will use voice commands as an input method for certain parts of your system.

5. What’s the difference between cohesion and coupling?

• Cohesion refers to the ability of components to work together. The deeper the cohesion, the more a component can work with other components in the same system. 

• Coupling refers to how tightly two separate components are integrated with one another. The tighter the coupling, the harder it is for one component to make changes that affect another component.

6. Do you know the concept of the CAP Theorem?

The CAP theorem is a way of thinking about how to choose between different systems for a given task. It can be useful for distributed computing because it helps you decide which system is best for your particular problem. It’s a theorem that describes how you can’t have all three of these things:

• Consistency: Your data must always be consistent. If you ever change a piece of data, the result must be consistent with the old version of that data.

• Availability: Your system must be available all of the time, even if nobody is using it. If your system is down for maintenance or is unavailable for other reasons, you need to make sure that your data still remains valid and useful.

• Partition tolerance: Your system must tolerate at least one partition between two systems when one goes down; this means that if you have an actual network partition (like if there’s an unexpected power outage), your application needs to continue running through an alternative pathway.

7. What Does REST indicate in backend programming?

REST stands for Representational State Transfer. 

• It is a set of architectural principles that allow web applications to communicate with each other and with external services.

• RESTful services are easy to create since they don’t require any special coding. They just need to send their requests over HTTP and receive responses in the same way.

• This makes REST a great choice for backend development because it requires no additional setup or configuration on your part before you can get started building your app or service. 

• And since there’s no extra code required to make requests, you can focus on adding features instead of worrying about how those features will interact with each other or with other parts of your application (or even other applications).

8. What is continuous integration in CI/CD pipeline?

Continuous integration (also called CI) is a software development that involves integrating the code from your development team into a shared repository deploying new code every time a developer commits changes to the source code repository.  The benefits of continuous integration include the following:

• Reduced risk of broken builds and deployments due to changes in the code.
• Reduced risk of missed errors or bugs due to human error.
• Improved productivity by providing feedback on the status of individual builds rather than waiting for a complete build before knowing whether it succeeds or fails.

9. List a few performance-testing components. 

Components of performance testing include:

• Load testing with different browsers and operating systems
• Static code analysis
• Determining which performance issues are causing the most pain for your users
• Creating metrics to measure those issues, such as page loading time or user experience
• Using tools that allow you to analyze your data quickly, easily, and accurately

10. What’s the difference between acceptance and functional testing?

What’s the difference between acceptance testing and functional testing?

• Functional testing: It is an approach to software testing that focuses on ensuring that a program meets its requirements through testing. Functional testing is sometimes called “unit testing” since it’s all about ensuring that individual components of a system work as intended.

• Acceptance testing: Acceptance testing is more about assessing whether users will be satisfied with the final product. This type of testing often involves user acceptance testing and surveys. Acceptance testing aims to understand how users feel about your product or service before it’s ready for release.

11. Do you know the concept of Go Programming? 

Go is an open-source programming language developed by Google. It was created for the purpose of building high-performance systems. Go is easy to learn and implement, which makes it an ideal language for backend development. Some benefits include the following:

• Faster development: Go is designed to be fast. It’s built on top of the Google Go programming language, which has been optimized for performance. You’ll find that your code runs much faster than in other languages.

• Easy learning curve: Go is relatively new compared to other languages, but it’s also easy to pick up. It has an excellent community of developers who can assist you if you get stuck or require extra information about how something works. And there are plenty of resources available online that teach you all about Go programming!

• Easy concurrency: Go has many features that make it easier to write concurrent programs than in other languages like Ruby or Python. You don’t have to worry about threads or locks—the language takes care of this for you! This makes working with multiple processes much simpler too!

12. What is Containerization?

• Containerization is the process of separating a set of applications into discrete, self-contained groups that can be deployed and run independently on a single machine. 

• The term “container” comes from the fact that these separate groups run within the same operating environment, so all the applications are closely linked to each other and share resources.

13. What’s the high availability in backend development? Name some infrastructure that can help you maintain high availability. 

• High availability in backend development is the ability to maintain an online application or website even when there are multiple instances running at once. 

• This can be accomplished by having a redundant environment where all instances are identical except for their configuration and software.

• In a nutshell, high availability allows your application to continue its work even if one of the servers crashes, rather than having to shut down the entire service.

• There are many different types of infrastructure that can help you achieve high availability in your environment—from load balancers to database replication to cloud services.

14. Explain ACID Properties in Software Development.

The ACID property is an acronym for “Atomicity, Consistency, Isolation, and Durability.” This property defines the behavior of databases when they are updated with data.

• Atomicity means that each transaction must be completed completely before another can begin. If one transaction fails to complete, no other transactions will start.

• Consistency means that all changes made by one transaction must be applied to the data in all other transactions. If any changes are not consistent, they will not be applied to other transactions’ data.

• Isolation means that transactions must not depend on each other’s results before completing their work and are performed by independent processes.

• Durability means that changes made by one transaction must remain until either committed or rolled back by the process responsible for managing transactions (usually called ACID).

15. What is the difference between a GET and a POST request?

The difference between a GET and a POST request is that POST requests are used for sending data from the client to the server, while GET requests are used to get data from the server to the client.

• POST requests work by sending a form’s data back to the server with a specific action name. The form will return a response back to the client with a status code. This is called an “action” or “response” in HTTP requests. The action name is what tells your web browser what action you want to be performed when you click on something on your site, for example: “post” or “create.”

• GET requests are initiated by your browser, which sends a request containing cookies and other information about itself (known as headers) along with the actual URL of what it wants on its own server. The server returns this information in its response, which is then sent back to your browser.

16. Describe the application of asynchronous programming.

Asynchronous programming is a way to improve performance in the event that an API request takes a long time to complete. 

• This is especially important when you’re dealing with a web application or API, as it allows for a more responsive user experience and fewer interruptions for your users.

• Asynchronous programming can also reduce latency or improve scalability. 

For example, asynchronous programming would make sense if you were building an online casino or stock trading app. You wouldn’t want players to be able to see their cards before they’ve been dealt, and if you need to handle thousands of transactions per second, then you want to avoid blocking the user interface with each one.

17. What are the common issues with ORMs in backend development?

When it comes to ORMs and backend development, there are some common issues that developers can run into.

• The first issue is the sheer amount of code needed to create an ORM. The more complex the backend application, the more code you need to write. 
• Many ORMs do not provide full integration with existing tools. 

• Finally, some ORM systems require developers to build their own relational database instead of using one provided by them. This can be time-consuming and make the learning curve complex for new developers.

What’s Next?

I’ve just covered the tip of the iceberg! Stay tuned for more programming-specific (Java, Python, SQL) interview questions. Wish you all the best with your job application. Keep learning, and keep rocking!