As a Software Engineer at Toluna, you are a critical contributor to the technology that powers one of the world’s leading consumer insights platforms. Your work directly impacts how global brands gather, analyze, and interpret consumer data. You will be responsible for building, maintaining, and scaling the software solutions that allow Toluna to deliver real-time insights to its clients, ensuring high performance and reliability across a massive, data-driven ecosystem. This role requires a blend of core engineering discipline and a pragmatic approach to problem-solving. Whether you are working on the front-end interfaces that users interact with or the back-end systems that manage complex data flows, your work is central to the company’s ability to innovate. You will collaborate with cross-functional teams, including product managers and senior engineering leadership, to translate business requirements into robust, scalable technical implementations. Successful candidates at Toluna are those who can balance technical rigor with business agility. You will face challenges involving both legacy system maintenance and the development of new features, requiring you to be adaptable, communicative, and deeply invested in the quality of your code. Expect a fast-paced environment where your technical decisions have a measurable impact on the end-user experience.
HR Discussion
reportedEngage with HR to discuss your background and fit for the role.
What to demonstrate
- Engage with HR to discuss your background and fit for the role
- Depth in JavaScript
How to prepare
- Answer aloud and timed: Can you explain the difference between various sorting algorithms and when to use them?
- Answer aloud and timed: How would you implement a function to reverse a linked list?
Technical Rounds
reportedParticipate in one or more technical evaluations, which may include coding challenges or home assignments.
What to demonstrate
- Participate in one or more technical evaluations, which may include coding challenges or home assignments
- Depth in JavaScript
How to prepare
- Answer aloud and timed: What are the key differences between HTML5, CSS3, and modern JavaScript frameworks?
- Answer aloud and timed: Can you describe your experience with SQL and how you optimize database queries?
System Design Discussion
reportedEngage in discussions focused on system design to assess your technical skills.
What to demonstrate
- Engage in discussions focused on system design to assess your technical skills
- Depth in JavaScript
How to prepare
- Answer aloud and timed: How do you approach building a functional interface from scratch?
- Answer aloud and timed: Walk me through a challenging technical problem you solved; what was your process?
Final Team Interviews
reportedUndergo deep-dive technical evaluations with senior engineering leadership.
What to demonstrate
- Undergo deep-dive technical evaluations with senior engineering leadership
- Depth in JavaScript
How to prepare
- Answer aloud and timed: How do you handle debugging when a system behaves unexpectedly in a production environment?
- Answer aloud and timed: Given a specific logic puzzle, how would you structure the code to solve it efficiently?
PracHub editorial advice for the preparation topics above.
Think aloud
When solving coding problems, narrate your thought process. This helps the interviewer understand your logic, even if you run into a bug.
Prepare your stories
Use the STAR method (Situation, Task, Action, Result) to structure your answers to behavioral questions.
Know your resume
Be prepared to discuss every technical detail of the projects you have listed.
Show enthusiasm
We value candidates who are excited about the work we do. Research the company’s recent news and product developments.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Can you explain the difference between various sorting algorithms and when to use them?
Can you explain the difference between various sorting algorithms and when to use them?
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?
How would you implement a function to reverse a linked list?
How would you implement a function to reverse a linked list?
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 me through a challenging technical problem you solved; what was your process?
Walk me through a challenging technical problem you solved; what was your process?
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 specific logic puzzle, how would you structure the code to solve it efficiently?
Given a specific logic puzzle, how would you structure the code to solve it efficiently?
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?
Keep soft-deleted accounts from blocking re-registration
app_user holds user_id, tenant_id, email CITEXT, password_hash (NULL for SSO principals), email_verified_at, auth_version, status ('invited','active','suspended','deactivated'), created_at, updated_at, deleted_at. Two live accounts for one address inside a tenant must be impossible, but an address freed by a soft delete must be reusable, and the same tenant may delete and re-register it repeatedly. Write the uniqueness DDL for PostgreSQL 16, then the equivalent for MySQL 8 where partial indexes do not exist, and say what each permits once three deleted rows already hold that address.
Approach
- Start from what is actually unique: not (tenant_id, email), but (tenant_id, email) among live rows. PostgreSQL says that directly — CREATE UNIQUE INDEX app_user_live_email ON app_user (tenant_id, email) WHERE deleted_at IS NULL. A full constraint over the same two columns burns the address permanently the first time someone deletes an account.
- Keep case-insensitivity in the type or the index, never in the application: CITEXT as given, or UNIQUE (tenant_id, lower(email)) as an expression index where the extension is unavailable. A case-sensitive unique column is exactly how two accounts for one human appear.
- For MySQL 8 the predicate has to move inside the key: add a discriminator column that is a constant 0 while the row is live and is set to user_id on delete, with UNIQUE (tenant_id, email, deleted_marker). Live rows share the constant and still collide; deleted rows differ from each other and stop colliding.
- State the NULL variant and its dependency: leaving the marker NULL for deleted rows also works, because a unique index treats NULLs as distinct — true in MySQL, and true in PostgreSQL only under the default NULLS DISTINCT, which PostgreSQL 15 lets you reverse. Check the polarity against the three existing deleted rows: constant-on-live is what preserves the collision you want, and reversing it silently admits duplicate live accounts.
Follow-up
- A deleted account re-registers with the same address the next day. Do the old resource rows follow the new user_id, and how does the API keep the two principals apart?
- How do you honour an erasure request while resource_revision.actor_user_id still references this table?
Replace offset paging on the resource feed with keyset
resource holds resource_id, tenant_id, owner_user_id, title, body_ref, version, status ('draft','active','archived','deleted'), created_at, updated_at, deleted_at, with an index on (tenant_id, status, updated_at DESC, resource_id DESC). The listing endpoint returns active resources for one tenant, newest update first, 50 per page, today with LIMIT 50 OFFSET n. Tenants reach page 400 and rows are created while they read. Write the keyset query, define what the cursor carries and how it is encoded, and say which part of the index each predicate uses. Assume PostgreSQL 16.
Approach
- Name the two failures separately. OFFSET 20000 makes the server produce and discard 20,000 rows, so page cost grows with depth rather than with page size. Independently, any write that changes how many rows sort above the offset moves the window between two fetches, and the direction decides which anomaly you get: an insert lands at the head of updated_at DESC and pushes already-returned rows down past the boundary, so they are returned a second time; a delete above the offset, or a row whose updated_at is bumped above the cursor, pulls rows up and one is never returned at all. Nothing in the response reveals either.
- Write the seek: WHERE tenant_id = $1 AND status = 'active' AND (updated_at, resource_id) < ($2, $3) ORDER BY updated_at DESC, resource_id DESC LIMIT 50. The row-value comparison is one index range rather than a disjunction, and both columns are NOT NULL, which is what makes that comparison well defined.
- Map each predicate onto the index: tenant_id and status are equality on the leading columns, (updated_at, resource_id) is the range, and the ORDER BY matches the index order so no Sort node appears and the scan stops after 50 rows. The DESC in the definition only matters for mixed directions — a plain ascending btree on the same columns is read backwards for this query.
- Put both sort columns in the cursor and nothing the client can tamper with into another tenant: base64 of (updated_at, resource_id), validated server-side, with tenant_id taken from the principal.
Follow-up
- The client asks for 'jump to page 400'. What do you offer instead, and what does the honest version cost?
- Sort order becomes user-selectable across four columns. How many indexes is that, and which would you refuse to add?
What are the key differences between HTML5, CSS3, and modern JavaScript frameworks?
What are the key differences between HTML5, CSS3, and modern JavaScript frameworks?
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?
How do you approach building a functional interface from scratch?
How do you approach building a functional interface from scratch?
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?
What is your approach to handling API integrations in a distributed system?
What is your approach to handling API integrations in a distributed system?
Approach
- Say who the caller is and what they do when the call fails halfway.
- Define the identity of a request so a retry cannot double-apply it.
- Separate accepted, pending, failed and confirmed; they are different facts.
- Design the error taxonomy before the success shape; callers branch on it.
Follow-up
- What happens if the caller retries after a timeout?
- How does a client discover it is on an old version of this contract?
Exports duplicate a row range about once a week
Roughly once a week an export writes a file containing a duplicated range of rows. The affected job_run rows show attempt = 1, status = succeeded, one started_at, and a lease_owner naming a different host from the one whose logs show the job starting. Leases last 30 seconds and are heartbeated every 10 from inside the handler; lease_expires_at is computed on the worker and compared against the database's now(). Find the mechanism, and give a fix that holds even if you cannot fix the clocks.
Approach
- Start from the fact that eliminates the obvious answer. attempt = 1 means no retry was recorded, so this is not a re-run after failure; two workers ran the same row concurrently and the takeover path never touched the counter. lease_owner naming a host other than the one that started the job is the same statement from the other side.
- Enumerate the mechanisms that cause a premature takeover, then find the signal that separates them. Either the lease genuinely expired because the heartbeat did not fire, which is what happens when the heartbeat runs on the handler's own thread and the handler makes a long blocking call, or it only appeared expired because two clocks disagree, since lease_expires_at is written from the worker's clock and evaluated against the database's. The discriminator is the distribution: incidents clustered on the longest exports indict the heartbeat, incidents clustered on one host indict skew. Measure both, and measure each host's offset against the database directly.
- Read the reclaim query precisely. In PostgreSQL now() is transaction start time, not statement time, so a reclaimer holding a long transaction compares against an older timestamp than expected; clock_timestamp() is the statement-time function. This is worth ruling in or out before you redesign anything, because it changes which rows look expired.
- Remove the second clock rather than trying to synchronise it. Issue and extend the lease in the database, with lease_expires_at = now() + interval '30 seconds' in both the claim and the heartbeat, so exactly one clock is ever compared and worker skew stops mattering to this predicate.
Follow-up
- The displaced worker has already streamed half the file to object storage. What makes that side effect safe to repeat?
- You now count takeovers. What alert fires on that counter, and at what threshold?
Built from the rounds and topics Toluna candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Toluna loop
- Write out the reported sequence: HR Discussion, Technical Rounds, System Design Discussion, Final Team Interviews.
- 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 4 reported rounds, with the weakest marked.
02Work JavaScript
- Spend the session on JavaScript, which Toluna candidates report being tested on.
- Write one worked example in JavaScript and time yourself on it.
Deliverable: One timed worked example in JavaScript.
03Work Problem Solving (Coding Challenges)
- Spend the session on Problem Solving (Coding Challenges), which Toluna candidates report being tested on.
- Write one worked example in Problem Solving (Coding Challenges) and time yourself on it.
Deliverable: One timed worked example in Problem Solving (Coding Challenges).
04Work C
- Spend the session on C, which Toluna candidates report being tested on.
- Write one worked example in C and time yourself on it.
Deliverable: One timed worked example in C.
05Answer out loud: Technical Foundations
- Answer aloud, timed: Can you explain the difference between various sorting algorithms and when to use them?
- Answer aloud, timed: How would you implement a function to reverse a linked list?
Deliverable: Spoken answers to 2 reported Technical Foundations question(s), under time.
06Answer out loud: Problem Solving & Logic
- Answer aloud, timed: Walk me through a challenging technical problem you solved; what was your process?
- Answer aloud, timed: How do you handle debugging when a system behaves unexpectedly in a production environment?
Deliverable: Spoken answers to 2 reported Problem Solving & Logic question(s), under time.
07Answer out loud: Behavioral & Professional Background
- Answer aloud, timed: Tell me about a project you are particularly proud of and your specific role in it.
- Answer aloud, timed: How do you prioritize tasks when working under tight deadlines?
Deliverable: Spoken answers to 2 reported Behavioral & Professional Background 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.
Can you describe your experience with SQL and how you optimize database queries?
Can you describe your experience with SQL and how you optimize database queries?
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 debugging when a system behaves unexpectedly in a production environment?
How do you handle debugging when a system behaves unexpectedly in a production environment?
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 me about a project you are particularly proud of and your specific role in it.
Tell me about a project you are particularly proud of and your specific role in 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 prioritize tasks when working under tight deadlines?
How do you prioritize tasks when 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?
Describe a time you had a technical disagreement with a team member; how was it resolved?
Describe a time you had a technical disagreement with a team member; how was it resolved?
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 are you interested in the consumer insights space and Toluna specifically?
Why are you interested in the consumer insights space and Toluna specifically?
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
Can you describe your experience with SQL and how you optimize database queries?
- 02
How do you handle debugging when a system behaves unexpectedly in a production environment?
- 03
Tell me about a project you are particularly proud of and your specific role in it.
- 04
How do you prioritize tasks when working under tight deadlines?
How long does the interview process typically take?
The process varies by location and role, but we aim for efficiency. You can expect the stages to move relatively quickly once you enter the technical interview phase.
Toluna Software Engineer candidate reports ↗Should I expect a take-home assignment?
It is possible. Some roles include a technical homework assignment designed to assess your ability to build a small feature or solve a specific engineering problem independently.
Toluna Software Engineer candidate reports ↗How can I stand out during the interview?
Be proactive in your communication. Explain your thought process while coding, ask clarifying questions, and show a genuine interest in the specific challenges Toluna is solving.
Toluna Software Engineer candidate reports ↗Are there behavioral questions?
Yes, behavioral questions are a standard part of our process. We want to understand how you handle challenges and work within a team.
Toluna Software Engineer candidate reports ↗What topics does Toluna test in interviews?
Toluna interviews most often cover Quantitative Reasoning, JavaScript, Market Research, Sales Fundamentals (Account Executive), and Communication skills. The exact emphasis depends on the specific role you apply for.
Toluna 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.
- 01Toluna 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
Explore related engineering environments and compare the preparation focus.
Vercel Software Engineer Interview Guide
Debugging practice for Vercel software engineer prep built on a reproduction you trust, narrowing to the smallest failing input, and changing one variable per run so the result stays attributable.
Spotify Software Engineer Interview Guide
Timed practice for Spotify software engineer candidates who lose time to the clock: short problems taken end to end, then reviewed against a written rubric rather than a passing test run.
Shopify Software Engineer Interview Guide
Timed practice for Shopify software engineer candidates who lose time to the clock: short problems taken end to end, then reviewed against a written rubric rather than a passing test run.
Ramp Software Engineer Interview Guide
Systems practice for Ramp software engineer candidates, weighted toward payments and lending work: the load that actually arrives, the failure modes that matter there, and the invariants a partial outage must not break.