A technical interview for a junior IT position can be stressful—especially for those just entering the industry. Fortunately, it's something you can prepare for thoroughly. It's worth knowing what kind of knowledge recruiters expect, what questions might come up, and how to present yourself in the best light. Below, we share tips tailored to different specializations—Backend, Frontend, QA/Tester, and DevOps—since each emphasizes slightly different skills. At the end, you'll also find general advice on mindset, attitude, and soft skills questions, which may also come up during the interview.
How to use this guide?
Carefully read the part related to your specialization, as well as the general tips at the end. Try to put yourself in the recruiter’s shoes—think about what you would expect from a candidate for a similar role and what questions you would ask. Also, keep in mind that a job interview is a two-way conversation—you can (and should) ask questions, too, and assess whether the company is a good fit for you. With this approach, preparation will be easier and the interview itself more successful.
Backend Developer (Junior)
Scope of knowledge.
As a junior backend developer, you should have a solid grasp of programming fundamentals in your chosen language (e.g. Java, Python, C#, or JavaScript/Node.js), as well as an understanding of object-oriented programming principles and data structures. Familiarity with databases and SQL is essential—knowing only how to code in Java or Python won't be enough, as SQL is a core skill in backend development. It’s also useful to be familiar with:
Networking protocols and HTTP/REST (client-server architecture, JSON/XML formats, etc.)
Backend frameworks or libraries – such as Spring (Java), Django (Python), or Express (Node). You don’t need to be an expert, but understanding the basics of your company’s tech stack is helpful.
Version control systems (e.g. Git) and build tools (Maven/Gradle, npm, etc.)
Basic algorithms and data structures – some companies might ask you to solve a simple coding task (e.g. sorting, finding duplicates in an array).
Basic application security concepts (e.g. what SQL Injection is and how to prevent it).
Keep in mind that SQL and databases are a common denominator across many backend technologies. For example, 72% of PHP developers and 61% of Java developers report knowing SQL. In practice, this means that even if you apply for a role focused on a single language, you'll still need database-related knowledge.
Example technical questions.
Backend interviews often include questions assessing your understanding of databases, system architecture, and the programming language you use. Here are some typical questions you might encounter as a junior backend developer:
What is NoSQL and how does it differ from relational databases? – Your answer should explain that NoSQL refers to non-relational databases that store data in formats other than tables (e.g. JSON documents, graphs).
What is SQL Injection and how can you prevent it? – Be prepared to describe the mechanism of SQL injection and how to defend against it (e.g. parameterized queries).
What is microservice architecture? – You should be able to compare it with a monolithic architecture and mention that microservices are independent components communicating via APIs.
Explain the ACID principles in database transactions. – These are the four properties (Atomicity, Consistency, Isolation, Durability) that ensure transaction integrity.
(If you know a specific language like Java or Python) – Expect language-specific questions such as: “What is method overriding in Java?” (inheritance, @Override) or “What is a lambda function in Python?”
The range of topics can be broad, but questions typically focus on fundamentals—the recruiter wants to check whether you understand the essence of backend development, not whether you’ve memorized every API detail. Many example questions (with answers) can be found in industry articles—reviewing them and practicing your own answers is a good strategy.
Recommended learning resources.
When preparing for a backend developer role, use both documentation and practical tutorials:
Official documentation of your chosen language and framework – e.g. Java Docs or the Python.org tutorial. These help solidify your knowledge of syntax and standard libraries.
Online courses and e-learning – Platforms like Udemy, Coursera, or Codecademy offer backend courses (e.g. “Java for Beginners,” “Python Backend Development”). For self-learners, freeCodeCamp is a great, free source with a backend/API learning path.
Hands-on practice – Try building a small project, like a simple CRUD app with a database. Use your preferred framework (e.g. Spring Boot, Django, Flask) and upload your code to GitHub. This can serve as your portfolio.
Developer blogs and forums – Read dev blogs (e.g. Bulldogjob’s “Start in IT” section) and participate in forums like Stack Overflow or 4programmers. Polish-language Facebook/Discord groups focused on programming are also valuable—you’ll find answers and advice from more experienced peers.
Coding challenges and algorithms – Practice basic algorithm tasks on platforms like HackerRank, CodeSignal, or LeetCode (easy level). Not every company requires this, but practicing logic and coding under time pressure is always beneficial.
Remember to combine theory with practice. Knowing the concepts (like design patterns or types of databases) isn’t enough—it’s important to demonstrate your ability to apply them in code. If you’ve taken an online course, make sure to write some code on your own afterward instead of just repeating the instructor’s examples.
Common candidate mistakes (backend).
Junior backend candidates often make similar mistakes during interviews. Being aware of them can help you avoid them:
Overstating skills – Listing technologies on your resume that you haven’t really worked with is a fast track to failure—discrepancies between your claims and real knowledge are quickly exposed. Be honest about what you know.
Skipping the basics – Some candidates focus on the “flashy” parts of a language or framework but can’t explain core concepts. For example, someone used MongoDB but can’t explain how SQL differs from NoSQL, or completed a Spring Boot course but doesn’t understand REST APIs. Make sure you grasp the fundamentals behind the tools you’ve used.
Memorizing answers – Recruiters can tell if you're reciting memorized definitions without understanding. Instead of learning definitions by heart, practice explaining concepts in your own words.
Chaotic problem-solving – When given a coding task, panicking and jumping into coding without thinking can hurt your chances. A common mistake is trying to solve the problem before understanding it—better to pause, ask clarifying questions, and plan a step-by-step approach.
Not admitting gaps in knowledge – If you don’t know something, don’t guess or bluff. It’s better to say, “I haven’t encountered that yet, but I’m eager to learn. I assume it might be related to…” This approach is much better received than pushing a wrong explanation.
Neglecting testing and code quality – Backend development isn’t just “make it work.” Candidates often forget to mention unit testing, error logging, or exception handling—these details show a professional mindset. You don’t need to be an expert, but it’s a good sign if you mention that you’ve written simple tests or care about code readability.
Introduction A technical interview for a junior IT position can be stressful—especially for those just entering the field. Fortunately, it’s something you can prepare for thoroughly. It helps to know what kind of knowledge recruiters expect, what questions might come up, and how to present yourself in the best possible light. Below, we share tips for various specializations—Backend, Frontend, QA/Tester, and DevOps—since each of them emphasizes slightly different skills. At the end, you’ll also find general advice about mindset, attitude, and soft skills questions, which are also likely to be part of the interview.
How to use this guide Read the section that matches your specialization carefully, along with the general tips at the end. Try to put yourself in the recruiter’s shoes—think about what you would expect from a candidate applying for the same role, and what questions you would ask. Keep in mind that interviews are a two-way process—you’re also allowed to ask questions and check whether the company is a good fit for you. With that mindset, preparation will be easier and the interview itself more successful.
Backend Developer (Junior) Knowledge scope As a beginner backend developer, you should have a good grasp of programming fundamentals in your chosen language (e.g., Java, Python, C#, or JavaScript/Node.js) and understand object-oriented programming principles and data structures. Knowing databases and SQL is essential—coding in Java or Python alone won’t cut it, because SQL is a foundational tool in backend work. It also helps to be familiar with:
Network protocols and HTTP/REST (client-server architecture, JSON/XML formats, etc.).
Backend frameworks or libraries—like Spring (Java), Django (Python), or Express (Node). You don’t need to be an expert as a junior, but you should know the basics of the tech stack used in the company.
Version control systems (e.g., Git) and project build tools (Maven/Gradle, npm, etc.).
Basic algorithms and data structures—some companies might ask you to solve a simple coding task (e.g., sorting or finding a duplicate in an array).
Basic application security (e.g., what SQL Injection is and how to prevent it).
It’s worth noting that SQL and databases are a common denominator in many backend technologies—for example, 72% of PHP developers and 61% of Java developers report SQL knowledge. In practice, this means that even if you’re applying for a role focused on a specific language, you also need to understand database-related concepts.
Example technical questions In backend interviews, questions often assess your understanding of databases, system architecture, and the programming language you work with. Here are some common questions a junior Backend Developer might encounter:
What is NoSQL, and how is it different from relational databases? – A good answer should explain that NoSQL refers to non-relational databases that store data in formats other than tables (e.g., JSON documents, graphs).
What is an SQL Injection attack, and how can it be prevented? – You’re expected to describe how SQL Injection works and how to defend against it (e.g., query parameterization).
What is microservices architecture? – You should be able to compare it with monolithic architecture and mention independently deployable components communicating via APIs.
Explain the ACID properties in database transactions. – That is, Atomicity, Consistency, Isolation, and Durability—key features that ensure transaction integrity.
(If you know a specific language like Java or Python) – You may be asked language-specific questions, such as: “What is method overriding in Java?” (inheritance, @Override) or “What is a lambda function in Python?”
The list of potential topics is long, but the questions usually focus on fundamentals—the recruiter wants to see whether you understand backend essentials, not whether you can recall every method from the documentation. You’ll find many sample questions with answers in industry articles—it’s a good idea to go through them and try answering on your own.
Recommended learning resources As you prepare for a backend developer role, make use of both official documentation and hands-on tutorials:
Official documentation of your chosen language and framework—e.g., JavaDocs or the Python Tutorial from Python.org. This will help you structure your understanding of syntax and standard libraries.
Online courses and e-learning – Platforms like Udemy, Coursera, or Codecademy offer backend development courses (e.g., “Java for Beginners,” “Python Backend Development”). For self-learners, a great free resource is freeCodeCamp and its API/backend curriculum.
Practical exercises – Try building a small project—such as a basic CRUD app with a database. Use a framework like Spring Boot, Django, or Flask and publish your code on GitHub. This kind of project can become your portfolio.
Blogs and developer forums – Read programming blogs (e.g., the “Start in IT” section on Bulldogjob) and participate in forums like Stack Overflow or 4programmers. Polish Facebook and Discord groups focused on programming are also helpful—you can find answers to many questions and advice from more experienced peers.
Recruitment tasks and algorithms – Practice solving simple algorithm challenges on platforms like HackerRank, CodeSignal, or LeetCode (easy level). Not every company requires this, but it’s a great way to train your logical thinking and code under time pressure.
Remember to combine theory with practice while learning. Just knowing concepts (like design patterns or database types) isn’t enough—it’s important to apply them in code. If you took an online course, make sure to write at least a small part of an app on your own instead of just repeating examples.
Common candidate mistakes (backend)
Junior candidates often make similar missteps in backend interviews. Being aware of them will help you avoid them:
Overstating your skills – Listing technologies on your CV that you haven’t really worked with is a fast track to failure—any discrepancy between claimed and actual knowledge becomes obvious quickly. Be honest when describing your skills.
Lack of basics – Sometimes a candidate focuses on flashy language or framework features but can’t explain the fundamentals. For example, they used MongoDB but can’t explain the difference between SQL and NoSQL, or used Spring Boot in a course but don’t understand what REST API means. Make sure you understand the basic ideas behind the tools.
Rote learning – Recruiters can quickly tell if you’re just reciting memorized answers. Instead of learning definitions word-for-word, try to explain concepts in your own words.
Chaotic problem-solving – When given a problem or coding task, panicking and jumping into code without understanding the problem can hurt you. A common mistake is starting to code immediately—it's better to take a moment, ask clarifying questions, and design a step-by-step solution.
Not admitting when you don’t know something – If you don’t know the answer, don’t guess or try to bluff your way through. It’s better to say, “I haven’t encountered that yet, but I’d be eager to learn. I think it might be about…” This attitude is more appreciated than fumbling through a wrong explanation.
Ignoring code quality and testing – Backend work isn’t just about “making it work.” Candidates often overlook unit testing, error logging, or exception handling—small things that show a professional attitude. You don’t need to be an expert, but it helps if you at least mention writing simple tests or caring about code readability.