What to expect in a junior developer interview

Junior developer interviews typically have three layers. First, a technical screen — usually a short coding challenge or quiz to confirm you have the basics. Second, a technical interview — where an engineer walks through your approach to problems, asks about CS fundamentals, and looks at how you reason under pressure. Third, a behavioural round — where they check whether you're someone who can work in a team, ask for help when needed, and keep learning.

Most candidates over-prepare for the technical side and walk into the behavioural round completely cold. The questions below cover both. Read them all.

What "junior" actually means to interviewers

They're not expecting you to know everything. They're looking for sound fundamentals, intellectual honesty about what you don't know, and clear evidence that you can learn fast. The candidate who says "I'm not sure, but here's how I'd figure it out" often beats the one who bluffs their way through.

Technical fundamentals

These questions test whether you have the conceptual grounding to write maintainable code and reason about systems. You don't need to recite a textbook — you need to demonstrate that you understand the ideas and can apply them.

Questions 1–7 · Core Technical
Question 01
"Can you explain the difference between object-oriented and functional programming?"
What they're really asking
Can you discuss programming paradigms clearly? Do you understand that different problems suit different approaches?
How to answer it
Don't get lost in theory. Give a clear one-sentence definition of each, then illustrate with a concrete example. OOP organises code around objects that bundle state and behaviour together — great for modelling real-world entities. Functional programming treats computation as the evaluation of pure functions, avoiding shared state — ideal for data pipelines and parallel processing. Mention that most modern codebases use both, depending on the problem.
Question 02
"What is the difference between a stack and a queue? When would you use each?"
What they're really asking
Do you understand basic data structures — and more importantly, can you reason about when each is appropriate?
How to answer it
A stack is LIFO (Last In, First Out) — like a stack of plates. Use it for undo functionality, call stacks, expression parsing. A queue is FIFO (First In, First Out) — like a printer queue. Use it for task scheduling, breadth-first graph traversal, message queues. The key is matching the data structure to the access pattern your problem requires.
Question 03
"What is Big O notation and why does it matter?"
What they're really asking
Can you reason about performance? Do you understand that algorithmic complexity matters at scale?
How to answer it
Big O describes how the runtime or memory usage of an algorithm scales with input size. It matters because code that runs in 10ms on 100 records might take 10 minutes on 1 million records if it's O(n²). Give an example: a simple loop is O(n), a nested loop over the same array is O(n²), binary search is O(log n). You don't need to optimise everything — but you should know when something is going to bite you.
Question 04
"Can you walk me through what happens when you type a URL into a browser?"
What they're really asking
This is a classic systems knowledge question. They want to see how deep you can go and whether you understand how the web actually works.
How to answer it
Cover the main beats: DNS lookup converts the domain to an IP address → TCP connection is established (TCP handshake) → HTTPS negotiates a TLS handshake → HTTP request is sent to the server → server processes the request and returns a response → browser parses HTML, loads CSS/JS, renders the page. You don't need to go into every detail — but showing you understand the full journey from browser to server and back demonstrates real systems thinking.
Question 05
"What is the difference between SQL and NoSQL databases? When would you choose each?"
What they're really asking
Do you understand data storage trade-offs, not just syntax?
How to answer it
SQL databases store structured data in tables with a fixed schema — great for complex queries, relationships, and situations where data integrity is critical (e.g. financial records). NoSQL databases store data in flexible formats (documents, key-value, graphs) — better for unstructured data, high write throughput, or rapidly changing schemas. The honest answer is: use SQL unless you have a specific reason not to. Most junior devs overestimate how often NoSQL is the right call.
Question 06
"What is version control and how do you use Git in your daily workflow?"
What they're really asking
Can you work in a team codebase without breaking things? Do you understand why version control exists?
How to answer it
Explain what version control does (tracks changes, enables collaboration, allows rollback), then describe your actual workflow: branching off main for features, committing with descriptive messages, opening pull requests, resolving merge conflicts. Be honest about your experience level. If you've only used Git on personal projects, say so — but explain the commands you know and that you understand the concepts. Mention you're familiar with PRs and code review workflows even if you haven't done them professionally yet.
Question 07
"Can you explain what REST is and how RESTful APIs work?"
What they're really asking
Most junior devs will be consuming or building APIs from day one. Do you know the fundamentals?
How to answer it
REST (Representational State Transfer) is an architectural style for designing APIs. Key principles: stateless requests, resource-based URLs, standard HTTP methods (GET to retrieve, POST to create, PUT/PATCH to update, DELETE to remove). A RESTful API returns data (usually JSON) and uses HTTP status codes to communicate outcomes (200 OK, 201 Created, 404 Not Found, 500 Server Error). If you've built or consumed any APIs — even in a side project — give a concrete example.

Practise answering these out loud

Reading answers isn't the same as being able to explain them under pressure. InterviewZap asks you technical and behavioural questions, transcribes your spoken answers, and tells you exactly where your explanations are unclear or incomplete.

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Coding and problem-solving

These questions assess how you think through problems — not just whether you can produce correct code, but whether your process is systematic, communicable, and something a team can build on.

Questions 8–12 · Coding & Problem Solving
Question 08
"How do you approach debugging a piece of code that isn't working?"
What they're really asking
Can you debug systematically, or do you just change things randomly until something works?
How to answer it
Walk through your process: reproduce the bug consistently first, then isolate where it's happening (narrow the scope with logging or breakpoints), form a hypothesis about the cause, test that hypothesis, fix and verify. Mention tools you use — debugger, console.log/print statements, unit tests to confirm the fix. The key message: you treat debugging like a scientific process, not guesswork. Bonus points if you can describe a specific bug you tracked down and what it taught you.
Question 09
"What does it mean to write clean code? Can you give an example?"
What they're really asking
Do you think about maintainability, or just getting something to run?
How to answer it
Clean code is code that other developers (including future you) can read, understand, and modify without difficulty. Key principles: meaningful variable and function names, functions that do one thing, no unnecessary comments (the code should explain itself), consistent formatting, and avoiding duplication (DRY principle). Give a concrete before/after example if you can — even something as simple as renaming x to userAgeInYears demonstrates the point.
Question 10
"How do you approach a coding problem you haven't seen before?"
What they're really asking
This is often asked mid-technical interview, right before they give you a live coding challenge. They want to see your process.
How to answer it
Talk through it before you type. Start by restating the problem in your own words to confirm you understand it. Ask clarifying questions (edge cases, input format, constraints). Think out loud — sketch a brute-force approach first, even if it's not optimal, to establish a working baseline. Then consider whether there's a more efficient solution. Write readable code over clever code. Test with examples as you go. Interviewers care about your process at least as much as your solution — a candidate who talks through a wrong approach clearly is often rated higher than one who sits in silence and produces the right answer.
Question 11
"What is the difference between unit tests, integration tests, and end-to-end tests?"
What they're really asking
Do you understand testing beyond "does it run?"
How to answer it
Unit tests test a single function or component in isolation — fast, cheap, and great for catching logic errors. Integration tests test how multiple components work together — e.g. your API handler + database layer. End-to-end tests simulate a real user journey through the full system — slower and more expensive to maintain, but catch the bugs that only appear when everything is connected. The test pyramid: lots of unit tests, fewer integration tests, even fewer E2E tests.
Question 12
"Have you worked with any CI/CD pipelines? What do they do?"
What they're really asking
Have you worked in a professional-grade development environment, even on a side project?
How to answer it
CI (Continuous Integration) automatically builds and tests your code every time someone pushes to the repository — catching broken builds and failing tests before they reach production. CD (Continuous Deployment/Delivery) takes the passing build and automatically deploys it to staging or production. If you've set up a GitHub Actions workflow or seen a pipeline in a project, describe it. If you haven't, be honest and explain what you understand about the concept — then add that you're keen to learn it in practice.

Behavioural questions

Technical ability gets you to the interview. Behavioural answers decide whether you get the offer. Engineering teams work closely together — they need to know you can communicate, handle feedback, and keep learning without someone holding your hand.

Use the STAR method for these — Situation, Task, Action, Result.

Questions 13–20 · Behavioural
Question 13
"Tell me about a project you're proud of. What was your contribution?"
What they're really asking
Can you articulate what you built, your specific role in it, and what you actually learned?
How to answer it
Pick one project — personal, academic, or professional — and describe it clearly: what it does, what stack you used, what your specific contribution was, and what you'd do differently now. The reflection at the end is what separates a good answer from a great one. Showing you can critique your own work signals maturity. Don't just list technologies — tell the story of what was hard and how you solved it.
Question 14
"Describe a time you got stuck on a problem. How did you get unstuck?"
What they're really asking
How do you handle frustration? Do you know when to ask for help? Do you have a systematic approach?
How to answer it
Be honest and specific. Describe the problem, what you tried, when you realised you were spinning your wheels, and how you moved forward — whether that was stepping away, searching documentation, asking a colleague, or approaching it differently. The key message: you don't just sit there stuck indefinitely, and you're not too proud to ask for help after you've genuinely tried. Both are things good teams care about.
Question 15
"How do you handle receiving critical feedback on your code in a review?"
What they're really asking
Are you defensive about your code? Can you separate your identity from your output?
How to answer it
The right answer is that you welcome it. Code review is one of the fastest ways to learn — every comment is someone transferring knowledge to you. Give an example where feedback made your code genuinely better. Mention that you try to understand the reasoning behind the comment rather than just making the change mechanically. If you've ever pushed back on a suggestion and explained your reasoning — and the reviewer agreed — that's an even better story.
Question 16
"Tell me about a time you had to learn something new quickly."
What they're really asking
Can you self-direct your learning? This is critical for junior devs who will be expected to pick up new frameworks, tools, and domains constantly.
How to answer it
Use STAR. Choose a genuine example — a new language, framework, or tool you had to pick up under a deadline or to complete a project. Describe how you approached the learning: documentation, tutorials, building something small, asking questions. Emphasise the method as much as the outcome. Interviewers want to know that your learning process is repeatable, not that you happened to learn one specific thing.
Question 17
"How do you prioritise when you have multiple tasks or deadlines?"
What they're really asking
Can you manage your own workload? Will you need constant direction, or can you figure out what matters most?
How to answer it
Describe your actual approach: clarifying urgency vs. importance, communicating proactively when something might slip, breaking tasks into smaller chunks so you can make visible progress. Be honest if you're still developing this skill — but show that you're intentional about it. Mention that when priorities are unclear, you ask rather than assume.
Question 18
"Have you ever disagreed with a technical decision made by someone senior? What did you do?"
What they're really asking
Can you express a technical opinion respectfully? Are you a pushover, or someone who thinks critically?
How to answer it
The best answer shows that you raised the concern clearly and constructively, listened to their reasoning, and then either updated your view or accepted the decision with grace. "Disagree and commit" is a valued trait in engineering teams. What they don't want to hear: that you either said nothing (passive) or dug your heels in (inflexible). Show you can hold a technical opinion, make the case for it, and then move forward regardless of the outcome.
Question 19
"Where do you want to be in your career in three years?"
What they're really asking
Are you serious about developing as an engineer? Will this role be a meaningful step for you, or just a placeholder?
How to answer it
You don't need a perfectly mapped career plan. What they want to hear is that you have a sense of direction and that this role fits into it. Something like: "I want to become genuinely strong at [area] and get experience working on systems at scale. In three years I'd like to be operating as a solid mid-level engineer who can own features end-to-end without close supervision." Connect it back to what this role specifically offers you.
Question 20
"Do you have any questions for us?"
What they're really asking
Are you actually curious about this company and role, or are you just going through the motions?
How to answer it
Always have questions. Ones that work well for junior developers: "What does the onboarding process look like for junior devs — how long before someone is typically pushing code to production?" / "What does the code review culture look like here?" / "What are the main technical challenges the team is working through right now?" / "What do strong junior developers on this team typically have in common?" Avoid asking about salary or vacation time in the first interview. Avoid questions whose answers are obviously on the company website — it signals you haven't done the reading.

How to prepare

Reading these questions is the start. Being able to answer them confidently — out loud, under pressure, with a stranger watching — is a different skill entirely.

  • For technical questions: Don't just read the answer. Explain it out loud to yourself or someone else. If you can't explain it simply, you don't know it well enough yet.
  • For behavioural questions: Build a bank of 5–8 real stories from your projects, internships, or study. Each story should work for multiple questions depending on the angle you take.
  • For coding challenges: Practice on platforms like LeetCode, HackerRank, or Codewars. But also practice talking through your thinking — most live coding interviews care as much about your reasoning as your output.
  • Mock interviews: At least once before the real thing, do a timed mock interview with someone asking questions. The first time you answer out loud is always the worst — do it somewhere low-stakes.
One more thing

Junior interviews are also an assessment of your potential — not just your current skill. Show curiosity. Ask good questions. Admit what you don't know and explain how you'd find out. The best junior developers aren't the ones who know the most on day one — they're the ones who learn fastest once they're in.