As a Software Engineer at Kantar, you are at the intersection of high-scale data analytics and actionable business intelligence. You will be responsible for building, maintaining, and scaling the robust platforms that help the world’s leading brands understand consumer behavior. Your work directly influences how clients interpret complex market trends, making your contributions central to the company’s mission of delivering evidence-based insights. The environment is fast-paced and intellectually demanding, requiring a balance of rigorous technical execution and collaborative problem-solving. You will work within diverse, cross-functional teams to tackle challenges ranging from data processing and backend architecture to intuitive frontend development. Whether you are optimizing database queries or designing scalable microservices, your focus will always be on the reliability, performance, and impact of the solutions you deploy. ##### Tip While the interview process is generally collaborative, be prepared to demonstrate deep technical fundamentals. Successful candidates are those who can bridge the gap between complex engineering concepts and the practical business problems Kantar solves for its clients.
Initial Screening Call
reportedA call with a recruiter to assess your fit for the role.
What to demonstrate
- A call with a recruiter to assess your fit for the role
- Depth in Object-Oriented Programming (OOP)
How to prepare
- Be able to walk your CV end to end in two minutes, and say why this company specifically.
- Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.
Technical Rounds
reportedOne or more rounds focusing on technical skills through coding exercises and deep dives.
What to demonstrate
- One or more rounds focusing on technical skills through coding exercises and deep dives
- Depth in Object-Oriented Programming (OOP)
How to prepare
- Answer aloud and timed: Describe the difference between various SQL Joins and when to use them.
- Answer aloud and timed: What are the key differences between DDL and DML commands in SQL?
Behavioral Interview
reportedA discussion to evaluate cultural fit and behavioral aspects of your experience.
What to demonstrate
- A discussion to evaluate cultural fit and behavioral aspects of your experience
- Depth in Object-Oriented Programming (OOP)
How to prepare
- Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
- Re-read the description of the behavioral interview above and write down what you would ask to confirm before it.
PracHub editorial advice for the preparation topics above.
Master the Fundamentals
Do not neglect basics like OOPs and DBMS. These are frequently tested and serve as a baseline for your technical credibility.
Practice Live Coding
Whether it is an online platform or a whiteboard session, practice explaining your thought process while you write code.
Know Your Resume
Be prepared to discuss every project you have listed in detail. Interviewers often use your resume as a starting point for technical deep dives.
Prepare Questions
Always have insightful questions ready for your interviewers. This demonstrates your engagement and interest in the specific challenges of the team you are interviewing for.
Be Transparent
If you don't know an answer, it is better to explain your reasoning and how you would go about finding the answer rather than guessing.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Explain the difference between Call by Value and Call by Reference.
Explain the difference between Call by Value and Call by Reference.
Approach
- Say what the runtime actually does before reasoning about the code.
- Name what is shared across threads and what owns each piece of state.
- Identify the window where an invariant is briefly untrue.
- Distinguish a value from a reference to it, and say which one you handed out.
Follow-up
- What happens if two callers reach this at the same time?
- Where could this allocate more than you expect?
Write a function to perform basic operations on an Array.
Write a function to perform basic operations on an Array.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Solve a medium-level LeetCode style problem involving strings or greedy algorithms.
Solve a medium-level LeetCode style problem involving strings or greedy algorithms.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Given a dataset, how would you identify seasonal trends or outliers?
Given a dataset, how would you identify seasonal trends or outliers?
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Explain your approach to solving a Dynamic Programming problem.
Explain your approach to solving a Dynamic Programming problem.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Walk us through a piece of code you have written and explain how you would improve it.
Walk us through a piece of code you have written and explain how you would improve it.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Describe the difference between various SQL Joins and when to use them.
Describe the difference between various SQL Joins and when to use them.
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- Handle the rows that do not match: that is usually the actual question.
Follow-up
- How does the query change if that join becomes one-to-many?
- What happens to this when the table is ten times larger?
What are the key differences between DDL and DML commands in SQL?
What are the key differences between DDL and DML commands in SQL?
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- Handle the rows that do not match: that is usually the actual question.
Follow-up
- How does the query change if that join becomes one-to-many?
- What happens to this when the table is ten times larger?
Can you explain how you would optimize a slow-running database query?
Can you explain how you would optimize a slow-running database query?
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- Handle the rows that do not match: that is usually the actual question.
Follow-up
- How does the query change if that join becomes one-to-many?
- What happens to this when the table is ten times larger?
How do you manage Object-Oriented Programming (OOPs) principles in your code?
How do you manage Object-Oriented Programming (OOPs) principles in your code?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Keep one tenant's bulk export from starving projection updates
The worker fleet runs about 600 jobs/second out of job_run, claimed under a lease and heartbeated while running. Most handlers finish under 200 ms; exports run for minutes. One tenant enqueues 50,000 exports. Design the scheduling so that tenant's exports slow down and nothing else does: the queue split, the concurrency caps and where they are enforced, the claim query, and the backpressure signal that stops accepting new work. State the in-flight worker count each class needs at its arrival rate, and what the cap costs the tenant that hits it.
Approach
- Do the concurrency arithmetic first, because it determines the pool shapes. Required in-flight work is arrival rate times service time: 600/second of 200 ms handlers needs about 120 workers, while one export per second at 180 seconds needs 180 on its own. The long tail dominates any pool it shares, so a single pool sized from the mean is consumed by exports while 50 ms projections queue behind them. That is head-of-line blocking, and adding capacity does not fix it because the ratio is what is wrong.
- Split by job class rather than by priority. Priority inside one pool still lets a running export hold its worker for the next four minutes - there is no preemption for a handler already executing. Separate queues and separate worker processes give each class a floor the other cannot take.
- Enforce the per-tenant cap inside the claim, not at enqueue. Claim with SELECT ... WHERE status='queued' AND run_after <= now() AND job_type=$1 ORDER BY run_after, job_run_id FOR UPDATE SKIP LOCKED LIMIT 1, restricted to tenants currently under their cap. Derive the running count from rows in status 'running' with a live lease rather than from a counter incremented at claim and decremented at completion: the derived count self-heals when a worker dies, and the counter leaks a slot every time one does.
- Make the ordering fair over tenants instead of over jobs. Strict FIFO with a cap still forces the claim to scan past 50,000 rows belonging to a capped tenant before it finds anyone else's work, so cost grows with backlog depth. Pick the tenant first from a small per-tenant queue-depth summary, then claim within that tenant, which makes the scan proportional to the number of active tenants instead.
Follow-up
- An export outruns its lease, so two copies run. What must the handler do to make the second copy harmless, and what does it write to guarantee that?
- With a cap of 4, the tenant's 50,000 exports now take hours. What do you tell them, and does the answer change if they are the largest tenant on the platform?
p99 jumped on one listing filter while p50 stayed flat
After a release that added an owner_user_id filter to the resource listing, p99 rose from 90 ms to 1.9 s while p50 stayed at 40 ms. Traffic and row counts are unchanged. resource carries the index (tenant_id, status, updated_at DESC, resource_id DESC). The new query filters tenant_id and owner_user_id, orders by updated_at DESC, resource_id DESC, and takes 20 rows. On PostgreSQL, explain the shape of the regression, prove it from a query plan, and give the index you would add.
Approach
- Start from the shape. A flat p50 with a moved p99 means a subset of requests changed cost, not all of them, so the first job is naming the subset. Bucket the endpoint's latency by the tenant's row count; the natural hypothesis is that large tenants are a small share of requests and all of the tail.
- Get the plan for the new query on a large tenant with EXPLAIN (ANALYZE, BUFFERS). Expect an index scan over the tenant's range, a filter discarding most of it, then a Sort feeding the Limit, possibly reporting Sort Method: external merge Disk. Read actual rows on the scan node, not estimated.
- Explain why the existing index cannot serve it. A composite B-tree is seekable only as a left prefix, and with no equality predicate on status the scan cannot treat updated_at as an ordering, because rows in the tenant's range are ordered by status first. Everything matching must be read and sorted before LIMIT 20 can apply, so a tenant with 400,000 rows pays 400,000 rows to return 20.
- Add (tenant_id, owner_user_id, updated_at DESC, resource_id DESC). Equality on the first two columns leaves the index ordered by updated_at within that pair, so the plan becomes an index scan that stops after 20 rows with no Sort node. PostgreSQL can scan a B-tree backwards, so the DESC markers matter only if the two sort columns ever disagree in direction; keeping them explicit documents the order the keyset cursor depends on.
Follow-up
- The endpoint paginates with OFFSET. What does page 500 cost with your index, and what does the keyset version cost?
- How would you have caught this before release, given that a 10,000-row seed database produces the same plan shape at an unnoticeable cost?
Built from the rounds and topics Kantar candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Kantar loop
- Write out the reported sequence: Initial Screening Call, Technical Rounds, Behavioral Interview.
- For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.
Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.
02Work Object-Oriented Programming (OOP)
- Spend the session on Object-Oriented Programming (OOP), which Kantar candidates report being tested on.
- Write one worked example in Object-Oriented Programming (OOP) and time yourself on it.
Deliverable: One timed worked example in Object-Oriented Programming (OOP).
03Work Databases (DBMS)
- Spend the session on Databases (DBMS), which Kantar candidates report being tested on.
- Write one worked example in Databases (DBMS) and time yourself on it.
Deliverable: One timed worked example in Databases (DBMS).
04Work SQL (Querying)
- Spend the session on SQL (Querying), which Kantar candidates report being tested on.
- Write one worked example in SQL (Querying) and time yourself on it.
Deliverable: One timed worked example in SQL (Querying).
05Answer out loud: Technical Fundamentals
- Answer aloud, timed: Explain the difference between Call by Value and Call by Reference.
- Answer aloud, timed: How do you manage Object-Oriented Programming (OOPs) principles in your code?
Deliverable: Spoken answers to 2 reported Technical Fundamentals question(s), under time.
06Answer out loud: Coding and Problem Solving
- Answer aloud, timed: Write a function to perform basic operations on an Array.
- Answer aloud, timed: Solve a medium-level LeetCode style problem involving strings or greedy algorithms.
Deliverable: Spoken answers to 2 reported Coding and Problem Solving question(s), under time.
07Answer out loud: Behavioral and Role Fit
- Answer aloud, timed: Describe a challenging project from your past and your specific contribution to it.
- Answer aloud, timed: How do you handle situations where there is a disagreement on technical direction within your team?
Deliverable: Spoken answers to 2 reported Behavioral and Role Fit question(s), under time.
Expand any day for tasks and deliverables. Your progress is saved on this device.
Behavioural rounds judge the decision you made and what it cost.
Describe a challenging project from your past and your specific contribution to it.
Describe a challenging project from your past and your specific contribution to it.
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
How do you handle situations where there is a disagreement on technical direction within your team?
How do you handle situations where there is a disagreement on technical direction within your team?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
Tell us about a time you had to learn a new technology quickly to solve a problem.
Tell us about a time you had to learn a new technology quickly to solve a problem.
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
How do you prioritize tasks when you are working under tight deadlines?
How do you prioritize tasks when you are working under tight deadlines?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
Why do you want to apply your engineering skills specifically to the data and insights domain?
Why do you want to apply your engineering skills specifically to the data and insights domain?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
- 01
Describe a challenging project from your past and your specific contribution to it.
- 02
How do you handle situations where there is a disagreement on technical direction within your team?
- 03
Tell us about a time you had to learn a new technology quickly to solve a problem.
- 04
How do you prioritize tasks when you are working under tight deadlines?
How long does the entire interview process take?
The timeline varies, but generally, it spans from a few weeks to a month. Factors like team availability and the specific seniority of the role can influence the speed of the process.
Kantar Software Engineer candidate reports ↗Are the technical rounds conducted on an IDE or paper?
Practices vary by team and location. Some rounds involve online coding platforms, while others may be pen-and-paper or whiteboard-style tests. Be prepared for both.
Kantar Software Engineer candidate reports ↗What is the best way to stand out?
Focus on your fundamentals. Interviewers at Kantar are impressed by candidates who can explain the "why" behind their code, demonstrate a clear problem-solving process, and show genuine interest in the company’s mission.
Kantar Software Engineer candidate reports ↗Is there a specific emphasis on a particular tech stack?
While Kantar uses a variety of tools, a strong foundation in Java, Python, and SQL is consistently relevant across most engineering teams.
Kantar Software Engineer candidate reports ↗What topics does Kantar test in interviews?
Kantar interviews most often cover Python, SQL, Case study analysis, Excel, and SQL Joins. The exact emphasis depends on the specific role you apply for.
Kantar Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.
- 01Kantar Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
Candidate reports · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
PracHub page · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
PracHub page · Accessed 2026-09-22
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