At Lockton Companies, a Software Engineer does not just write code; they build the proprietary platforms, risk assessment tools, and actuarial valuation systems that drive the world's largest independent insurance brokerage. Because Lockton Companies operates without the pressure of public shareholders, the technology team has the unique freedom to focus on long-term client-centric solutions. Your work as a Software Engineer will directly impact how brokers, risk analysts, and actuaries analyze complex risk profiles, price policies, and deliver specialized consulting to global clients. Depending on the specific team you join, you might find yourself working as an Actuarial Developer building complex mathematical modeling engines, or as a Software Engineer focusing on property risk systems. These systems process vast amounts of exposure data, requiring highly performant, scalable, and secure code. Engineers here work in a collaborative environment where technical skills are deeply integrated with business domain knowledge. By joining the technology team at Lockton Companies, you will work on modernizing legacy insurance workflows, developing predictive analytics platforms, and creating intuitive user interfaces. It is a highly collaborative and intellectually stimulating environment where your technical decisions have a visible, direct impact on the company's bottom-line performance and client satisfaction.
Virtual Screening
reportedInitial screening via Microsoft Teams focusing on career background, technical experience, and role alignment.
What to demonstrate
- Initial screening via Microsoft Teams focusing on career background, technical experience, and role alignment
- Depth in Basic Technical Questions
How to prepare
- Answer aloud and timed: Explain the difference between an abstract class and an interface, and when you would use each.
- Answer aloud and timed: How do you optimize a slow-running SQL query, and what is the role of indexing in database performance?
Final Round Interview
reportedConducted either in-person at regional offices or as a virtual panel with hiring managers and directors.
What to demonstrate
- Conducted either in-person at regional offices or as a virtual panel with hiring managers and directors
- Depth in Basic Technical Questions
How to prepare
- Answer aloud and timed: Describe the principles of object-oriented programming and how you have applied them in your recent projects.
- Answer aloud and timed: What are the differences between value types and reference types in your primary programming language?
PracHub editorial advice for the preparation topics above.
Understand the Business Model
Take time to learn what an insurance broker does and how it differs from an insurance carrier. Showing that you understand Lockton's client-first advisory model will make a fantastic impression on the hiring managers.
Be Prepared for Behavioral Scenarios
Use the STAR method (Situation, Task, Action, Result) to structure your answers to behavioral questions. Focus on outcomes and highlight how you collaborated with others to achieve success.
Lockton values long-term career growth
During your interviews with directors and managers, express your interest in growing with the company and learning the business domain over time.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
What are the differences between value types and reference types in your primary programming language?
What are the differences between value types and reference types in your primary programming language?
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?
Collapse a redelivered event batch into per-aggregate high-water marks
You drain a batch of up to 5,000,000 events, each (aggregate_id BIGINT, aggregate_version INT, event_type, payload). The log guarantees order within one aggregate only; the batch merges 64 partitions, and a relay failover has redelivered a range, so an older version for an aggregate can appear after a newer one. Given a map of last_applied_version per aggregate, produce the events worth applying, at most one per (aggregate_id, version), plus the count discarded. Target O(n) time. State the memory for 2,000,000 distinct aggregates and what you do when it does not fit.
Approach
- One pass, one hash map from aggregate_id to the highest version kept, and a discard counter. An event whose version is at or below last_applied_version for its aggregate is dropped without further work, which is the whole reason the event carries its version rather than a delta. O(n) expected time, O(d) space in distinct aggregates.
- Keep the maximum, never the last occurrence. The redelivered range means the final appearance of an aggregate in the batch can be an older version than one seen earlier in the same batch, so last-wins applies stale state over newer state and the projection regresses with no error anywhere.
- Cost the memory instead of calling it large: an 8-byte key plus a 4-byte version is 12 bytes of payload, and an open-addressed table held at a 0.7 load factor costs roughly 17 bytes per entry before per-slot metadata, so 2,000,000 aggregates is tens of megabytes in a native layout and several times that in a runtime that boxes both key and value.
- If the distinct set exceeds memory, partition on hash(aggregate_id) mod P and reduce each partition independently. Every event for one aggregate hashes to the same partition, so the per-partition result is exact and the merge is concatenation rather than a second reduction.
Follow-up
- The payload is a patch rather than a snapshot, so applying only the highest version loses the intermediate changes. What changes in your reduction?
- How do you detect that version 7 arrived while version 6 was never delivered, and what should the consumer do about the gap?
Merge partitioned event streams into one ordered feed with bounded lateness
The read-model service consumes 64 log partitions carrying about 4,000 events per second in total. Each partition is ordered within itself, but partitions drift by up to 30 seconds, and the activity feed must present a tenant's events in occurred_at order. Produce the merge. State its complexity, the buffer it requires in events and in bytes, what happens when one partition is idle, and what you do with an event that arrives after you have already emitted its position. Payloads average 1 KB.
Approach
- Merge with a min-heap over the 64 partition heads keyed on (occurred_at, event_id): O(log P) per event and O(n log P) overall. The tie-break on event_id is what makes the output deterministic when two partitions carry the same millisecond, which matters because the feed is paginated and a non-deterministic order reorders pages under the reader.
- Emitting the heap head is only correct once every partition has produced everything up to that timestamp, so the emit condition is a watermark: the minimum across partitions of the highest occurred_at seen, less the allowed lateness. Events are held until the watermark passes them, which is what turns individually ordered streams into a jointly ordered one.
- Size the buffer from the lateness rather than guessing: 4,000 events per second times 30 seconds is 120,000 buffered events, and at 1 KB each about 120 MB of heap. That number is the real price of the ordering guarantee and belongs in front of whoever asked for it.
- Handle the idle partition explicitly, because it fails the feed rather than corrupting it: a partition with no traffic never advances its own maximum, so the watermark freezes and output stops entirely. Either every partition emits a periodic idle marker carrying the broker's current time, or the watermark falls back to wall clock for a partition silent beyond a threshold.
Follow-up
- The lateness budget is raised to five minutes. What is the new buffer, and what besides memory changes?
- The consumer restarts. Where does it resume from, and what does the feed look like for the first 30 seconds?
How do you optimize a slow-running SQL query, and what is the role of indexing in database performance?
How do you optimize a slow-running SQL query, and what is the role of indexing in database performance?
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 approach structuring a database schema for an application that needs to track historical changes in
How do you approach structuring a database schema for an application that needs to track historical changes in client policy data?
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?
Explain the difference between an abstract class and an interface, and when you would use each.
Explain the difference between an abstract class and an interface, and when you would use each.
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?
Describe the principles of object-oriented programming and how you have applied them in your recent projects.
Describe the principles of object-oriented programming and how you have applied them in your recent projects.
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 would you design a data ingestion pipeline to process large daily files containing property risk metrics?
How would you design a data ingestion pipeline to process large daily files containing property risk metrics?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
Explain how you would design an API that allows external partners to securely query risk assessment reports.
Explain how you would design an API that allows external partners to securely query risk assessment reports.
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
Edge instances grow 400 MB per hour until the nightly restart
Edge API instances start at 700 MB resident and grow about 400 MB/hour; a nightly rolling restart has hidden it for weeks. Growth continues unchanged when request rate halves overnight, p99 degrades in the last hours before an instance is recycled, and heap used immediately after a forced full GC rises monotonically. The service holds no product state. Name the discriminating measurement that separates the plausible causes, give the most likely cause, and give the fix and how you would verify it.
Approach
- Separate resident memory from live heap first, because they fail differently. Resident size can grow from fragmentation, native buffers or thread stacks while the heap is flat; heap used after a full GC rising monotonically is the measurement that says objects are reachable and not being released. You already have it, so this is retention, not fragmentation, and that closes off half the candidate list.
- Use the rate's independence from traffic as the discriminator. Growth that continues at half the request rate rules out per-request objects that are merely slow to collect and points at a structure that grows with distinct values observed rather than with call volume. Write the candidates that have that property: a metrics registry keyed on a high-cardinality label, an unevicted cache, an interner, a per-key lock map.
- Take two heap snapshots an hour apart and diff by retained size, reading the dominator tree, not by allocation count or instance count. Expect one root holding a map with millions of entries, then follow the reference chain to the code that inserts and never removes. Allocation profilers point at churn, which is the wrong signal here.
- The candidate that fits this service is an observability label carrying an identifier, such as a request path recorded before templating so that /v1/resources/48213 becomes its own metric series. That grows with distinct ids seen, is independent of rate, and explains the late p99 degradation, since GC cost rises with the size of the live set.
Follow-up
- Post-GC heap is now flat but resident size still creeps. What are you looking at, and does it matter?
- How would you have detected this before an OOM, given the nightly restart masked the trend?
Built from the rounds and topics Lockton Companies candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Lockton Companies loop
- Write out the reported sequence: Virtual Screening, Final Round 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 2 reported rounds, with the weakest marked.
02Work Basic Technical Questions
- Spend the session on Basic Technical Questions, which Lockton Companies candidates report being tested on.
- Write one worked example in Basic Technical Questions and time yourself on it.
Deliverable: One timed worked example in Basic Technical Questions.
03Work Actuarial Software Development (Domain Knowledge)
- Spend the session on Actuarial Software Development (Domain Knowledge), which Lockton Companies candidates report being tested on.
- Write one worked example in Actuarial Software Development (Domain Knowledge) and time yourself on it.
Deliverable: One timed worked example in Actuarial Software Development (Domain Knowledge).
04Work Technical Screening
- Spend the session on Technical Screening, which Lockton Companies candidates report being tested on.
- Write one worked example in Technical Screening and time yourself on it.
Deliverable: One timed worked example in Technical Screening.
05Answer out loud: Technical & Core Programming
- Answer aloud, timed: Explain the difference between an abstract class and an interface, and when you would use each.
- Answer aloud, timed: How do you optimize a slow-running SQL query, and what is the role of indexing in database performance?
Deliverable: Spoken answers to 2 reported Technical & Core Programming question(s), under time.
06Answer out loud: Domain & Practical Problem-Solving
- Answer aloud, timed: How would you design a data ingestion pipeline to process large daily files containing property risk metrics?
- Answer aloud, timed: Describe a time when you had to write code to perform complex mathematical or statistical calculations. How did you ensure accuracy?
Deliverable: Spoken answers to 2 reported Domain & Practical Problem-Solving question(s), under time.
07Answer out loud: Behavioral & Cultural Alignment
- Answer aloud, timed: Describe a situation where you had to collaborate with non-technical stakeholders, such as actuaries or business brokers, to define project requirements. How did you ensure clear communication?
- Answer aloud, timed: Tell me about a time when you disagreed with a technical decision made by a teammate. How did you resolve the conflict?
Deliverable: Spoken answers to 2 reported Behavioral & Cultural Alignment 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.
How do you handle exception management and logging in a distributed application?
How do you handle exception management and logging in a distributed application?
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 when you had to write code to perform complex mathematical or statistical calculations. How di
Describe a time when you had to write code to perform complex mathematical or statistical calculations. How did you ensure accuracy?
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 situation where you had to collaborate with non-technical stakeholders, such as actuaries or busine
Describe a situation where you had to collaborate with non-technical stakeholders, such as actuaries or business brokers, to define project requirements. How did you ensure clear communication?
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 time when you disagreed with a technical decision made by a teammate. How did you resolve the
Tell me about a time when you disagreed with a technical decision made by a teammate. How did you resolve the conflict?
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 project that did not go according to plan. What went wrong, what did you learn, and how did you han
Describe a project that did not go according to plan. What went wrong, what did you learn, and how did you handle 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?
Why do you want to work at an independent, family-owned brokerage like Lockton Companies rather than a traditi
Why do you want to work at an independent, family-owned brokerage like Lockton Companies rather than a traditional public tech company?
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
How do you handle exception management and logging in a distributed application?
- 02
Describe a time when you had to write code to perform complex mathematical or statistical calculations. How did you ensure accuracy?
- 03
Describe a situation where you had to collaborate with non-technical stakeholders, such as actuaries or business brokers, to define project requirements. How did you ensure clear communication?
- 04
Tell me about a time when you disagreed with a technical decision made by a teammate. How did you resolve the conflict?
How technical are the software engineering interviews at Lockton Companies?
The interviews are highly practical. While you need a strong understanding of coding principles, databases, and system design, you will not face highly abstract, competitive-programming-style algorithms. The focus is on your ability to build real, maintainable software.
Lockton Companies Software Engineer candidate reports ↗What is the work culture like for engineers?
The culture is highly collaborative, supportive, and entrepreneurial. Because Lockton Companies is privately held, there is less bureaucratic red tape, allowing engineering teams to move quickly, experiment, and have a tangible impact on business operations.
Lockton Companies Software Engineer candidate reports ↗Does Lockton Companies offer remote or hybrid work options?
Yes, Lockton Companies generally supports a hybrid work model. Specific expectations vary by office location (such as London, Kansas City, or Minneapolis) and the specific team, but most engineering roles offer a balance of remote flexibility and in-office collaboration.
Lockton Companies Software Engineer candidate reports ↗How fast does the hiring team make a decision?
The interview process is known for being exceptionally efficient. Because the process typically consists of only two interview stages, candidates often receive feedback and next steps within a couple of weeks of their initial conversation.
Lockton Companies Software Engineer candidate reports ↗What topics does Lockton Companies test in interviews?
Lockton Companies interviews most often cover Problem Solving, Behavioral Interviewing, Stakeholder Management, In-Person Interviewing, and Communication Skills. The exact emphasis depends on the specific role you apply for.
Lockton Companies 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.
- 01Lockton Companies 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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