Top 10 back-end developer interview questions and answers

Are you a back-end developer preparing for an upcoming interview? Or, are you a recruiter looking to hire an expert back-end developer? In either case, you must have an idea of the back-end developer interview questions, and the curated list below offers you just that.

Last updated on May 19, 2022

Back-end developers create databases, scripts, and website architecture. Back-end developers work in tandem with front-end developers to provide server-side logic to the user interface elements. Whether you are a back-end developer looking for a job or a recruiter looking to hire a back-end developer, the back-end technical interview questions given here will help you. Once you have an overall idea of the back-end interview questions, you can frame more such questions or find answers to similar questions as per need.

Back-end developer interview questions and answers


Differentiate between software architecture and software design.

Software architecture refers to the program structure. As such, it can be understood as the bare skeleton of a program. Software design refers to the actual implementation of the code for the software requirements. So, software architecture can be considered as the program blueprint and software design can be considered as the process of how to build the program. As far as development is concerned, software design gets into the details. Both software architecture and software design are two separate processes that work together to form an integrated development process.


Talk about continuous integration and continuous delivery.

Continuous integration and continuous delivery are two interconnected software engineering processes. Continuous integration is a process that takes place in an ongoing manner to ensure that the program is built and tested regularly. Continuous delivery, on the other hand, is the ongoing development process that takes place in the latter part of the program lifecycle just before the production. These two processes form a cohesive automated process that keeps the work on track and increases production speed by getting rid of the inconsistencies between the development and operations teams.


How can you build scalability into a software program?

Scalability is an important aspect to be considered for enhancing productivity, especially concerning higher user demands and adaptation of functions and elements to higher amounts of user data. To determine the lifetime value of a software program, one must check its scalability. Lack of scalability warrants the need for rewriting the application with a new tech stack that adapts to the growth in audience. The scalability of a program can increase with features like cache, states, API, sort, and asynchronous programming. Moreover, tools like databases and frameworks have greater scalability than some others.


Why is Microservices architecture used?

Microservices architecture is characterized by integrating several small but independently deployable services into one application. It makes the operation more versatile as different programming languages can be used for writing individual services. Thus, different languages can be leveraged for different services. Maintenance is also easier as, even though the services are integrated, they are loosely connected. The microservices architecture model works well with and is preferred by larger teams, however, it may not be completely free of challenges like debugging.


What are NoSQL databases? Mention different types of NoSQL databases.

With the increase in big data, the internet has become a complex place. NoSQL databases help solve this problem. The NoSQL databases are neither traditional nor relational database management systems. NoSQL stands for ‘Not Only SQL’. With the growing amounts of data, a large percentage, close to 85%, is unstructured, messy, and complicated. NoSQL database handles and sorts such data. Thus, NoSQL offers a storage and retrieval mechanism for data that is modeled using other means and not the tabular relations used in RDBMS.

Types of NoSQL databases include:

  • Graph
  • Key-Value
  • Document Oriented
  • Column Oriented


Explain SQL injection.

An SQL injection can destroy the database by injecting malicious code or hack your database by injecting a hacking code. This occurs because there is little separation between the program code and the user input. SQL injection is a common type of injection attack on databases.

An injection attack can be prevented in the following ways:

  • Prepare statements with queries that have defined parameters
  • Have pre-defined and stored procedures
  • Have a validation process for the input whereby you can blacklist or whitelist the input
  • Use the principle of least privilege, i.e. do not provide premium administrator type access to the public database server. So, even if the hacker is able to hack into the application, it would not compromise the integrity of the database as they wouldn’t be able to access it.


Differentiate between acceptance and functional tests.

The differences are as follows:

Functional testing: Functional testing is done to verify whether the product, especially the application, is working as required or not. It ascertains whether the created software meets the business needs.

Acceptance testing: Acceptance testing is done to validate whether or not you built the right product. It validates that the product meets the customer’s needs. Acceptance tests ascertain that the user (customer) is actually benefiting from the product and is using it for the purpose it was meant for.


Mention some performance testing steps.

Below are some performance testing steps:

  • Determine the environment for testing
  • Finalize what performance metrics to use
  • Create a plan and design for the performance test
  • Configure the environment for the test
  • Implement the design for the test
  • Execute the performance tests
  • Conduct test analysis, create test report, and advise retest for underperforming applications


Mention some advantages of Web Services.

Web Services have the following advantages:

  • Interoperability: Web services can be accessed over the network and run using HTTP/SOAP protocols. For transporting data, web services use XML/JSON, thus, they can be rendered using different programming languages. For example, a web service that is written in Java is accessible over the network, runs on HTTP/SOAP protocol, and uses XML/JSON to transport data, hence it can be developed in any programming language. Web service can be written in java programming with PHP as the client and vice versa.
  • Reusability: Many client applications can use the same web service at the same time.
  • Loose Coupling: Web services client code does not depend on server code, thus, loose coupling is possible in the application.
  • It is easy to deploy and integrate, exactly like web applications.
  • Several versions of the service can run at the same time.


Differentiate between Clustered and Non-clustered indexes?

A Clustered index physically stores the rows on the disk in the order they appear on the index. Thus, only one Clustered index is possible. A Clustered index tells the database to store values that are close next to one another on the disk.

A Non-clustered index has a second list with pointers to the physical rows. There can be several Non-clustered indexes, every new index increases the time for writing new records.

If all columns are needed as is, then reading from a Clustered index is faster. You need not go to the index and table in that order. However, if the data must be rearranged, writing to a table with a Clustered index can slow down the process.

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Wrapping up

Now that you have gone through some of the important back-end interview questions, you know what type of questions can be asked and you can prepare accordingly. However, the interview is usually conducted in parts, and the back-end technical interview questions are just one part of the interview. There are many things to consider while hiring back-end developers also the candidates must be prepared for questions about their communication, project management, team management, social skills, etc. The recruiters must ensure that the back-end developer they hire is a great fit for the company’s culture.

If you want to apply for senior back-end developer roles in top Silicon Valley companies, you can take the Turing test and apply for roles in these companies. Or, if you want to hire from the top 1% back-end developers, Turing can help you do so.

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