Software developer interview questions usually fall into four groups: technical knowledge, practical problem solving, past experience and working style. Knowing which group a question belongs to makes it much easier to answer well. This page sets out the questions that come up most often in South African developer interviews, what the interviewer is actually assessing, and how to prepare answers grounded in your real duties.
What Interviewers Are Assessing
Most interviewers are trying to establish three things: whether you can do the technical work, whether you can reason through a problem you have not seen before, and whether you will work well with the existing team. Technical questions test the first, practical exercises the second, and behavioural questions the third. Answers that connect back to work you have genuinely done are consistently stronger than textbook definitions.
Common Technical Questions
These check foundational understanding. Answer plainly, then give a short example of where it mattered in your work.
- Explain the difference between an abstract class and an interface, and when you would use each.
- How do you handle errors and exceptions in the language you use most?
- What is the difference between synchronous and asynchronous processing?
- How would you optimise a slow database query?
- Explain how you would design a REST API for a given resource.
- What is the purpose of an index, and when can an index hurt performance?
- How do you manage dependencies and versioning in your projects?
- Describe your approach to writing automated tests.
Practical and Problem-Solving Questions
These may be a live coding exercise, a take-home task or a whiteboard discussion. The interviewer is watching how you think, not only whether you reach the answer. Talk through your reasoning, state your assumptions, and say when you would look something up rather than pretending to certainty.
- Given a described feature, how would you break it into deliverable tasks?
- Walk me through how you would debug a bug that only appears in production.
- How would you approach integrating an unreliable third-party API?
- You are asked to deliver in half the time you estimated. What do you do?
- How would you migrate a large table without downtime?
Behavioural and Situational Questions
These explore how you work with other people and how you handle pressure. Structure answers around the situation, what you did and what resulted, keeping the focus on your own contribution.
- Tell me about a technical decision you got wrong and what you learned.
- Describe a time you disagreed with a colleague about an approach.
- How do you give feedback in a code review?
- Tell me about a project that slipped. What caused it and what did you change?
- How do you explain a technical constraint to a non-technical stakeholder?
- Describe how you prioritise when everything is marked urgent.
Questions About Your Duties and Experience
Interviewers will probe the responsibilities listed on your CV, so make sure you can speak to every line of it in detail. Expect to be asked what you personally did versus what the team did, what you would do differently now, and how large the systems you worked on actually were. Preparing this is much easier if your CV duties were written specifically in the first place, which is covered in software developer duties for CV.
Questions Worth Asking the Interviewer
Asking considered questions signals genuine interest and helps you judge the role.
- How is work prioritised, and who decides?
- What does the deployment and release process look like?
- How much of the codebase is covered by automated tests?
- What is the on-call or production-support expectation?
- How are technical decisions documented and revisited?
- What does progression look like for this role?
How to Prepare
Re-read the job advert and map each requirement to something you have done. Revise the fundamentals of your main language, practise explaining past projects out loud, and prepare two or three examples flexible enough to answer several behavioural questions. Review the duties expected of the role you are applying for so your answers align with them, which you can do using Software Developer Duties. For other roles in this cluster, see professional job duties.
FAQs
What are the most common software developer interview questions?
The most common are questions about your main programming language and its fundamentals, how you would debug or optimise something, how you structure and test code, and behavioural questions about disagreements, missed deadlines and decisions you got wrong. Nearly every interview also probes the duties listed on your CV in detail.
What technical questions should I expect?
Expect questions on language fundamentals, error handling, API design, database querying and indexing, testing approach and version control. Many interviews include a practical exercise where the reasoning you show matters as much as the final answer.
How should I answer questions about my previous duties?
Answer with specifics: what you personally owned, the scale of the system, and the outcome. Be honest about where you contributed as part of a team. Interviewers routinely follow up on CV bullet points, so every line should be something you can discuss in depth.
How do I prepare for a coding exercise?
Practise talking through your reasoning while you work, since silent coding gives the interviewer nothing to assess. State your assumptions, start with a working solution before optimising, and say openly when you would consult documentation rather than guessing.
Which related page should I read next?
To prepare CV wording that stands up to questioning, use software developer duties for CV. To review what the role is expected to do, read Software Developer Duties.