USI Insurance Services Software Engineer Interview Guide

The 60-second brief

A Software Engineer at USI Insurance Services plays a pivotal role in transforming the way one of the world’s largest insurance brokerage and consulting firms leverages technology. You are not just writing code; you are building the proprietary platforms and data-driven solutions that allow USI to deliver specialized risk management and employee benefit strategies to thousands of clients. Whether you are joining as a Lead Software Architect, a Sr. Software Engineer, or a BI Developer, your work directly impacts the efficiency of brokers and the financial security of the clients they serve. The engineering team at USI focuses on creating a seamless integration between complex insurance data and actionable business intelligence.

This guide is scoped to a Software Engineer candidate at USI Insurance Services.

Focus areas

• Software Engineering
• BI Development
• Lead Software Architecture

The USI Insurance Services interview process

USI Insurance Services candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Recruiter Screen

Initial 30-minute conversation focused on your background and salary expectations.

What to demonstrate

• Initial 30-minute conversation focused on your background and salary expectations
• Depth in Software Engineering

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/Hiring Manager Screen

In-depth discussion with the technical team to assess your technical skills and fit.

What to demonstrate

• In-depth discussion with the technical team to assess your technical skills and fit
• Depth in Software Engineering

How to prepare

• Prepare two projects you led end to end, each with the decision you owned and what it cost.
• Have three questions about the team's roadmap and how success is measured in the first six months.

Final Panel

Rigorous stage involving multiple stakeholders to evaluate skills and cultural alignment.

What to demonstrate

• Rigorous stage involving multiple stakeholders to evaluate skills and cultural alignment
• Depth in Software Engineering

How to prepare

• Answer aloud and timed: What is the difference between a List and an Array in terms of memory and performance?
• Answer aloud and timed: How would you design a distributed caching system for a high-traffic web application?

Where candidates lose points

Master the STAR Method

When answering behavioral questions, always use the Situation, Task, Action, and Result format. USI interviewers appreciate structured, data-backed answers that highlight your specific contributions.

Focus on the "Why

During technical discussions, don't just explain what you did; explain why you chose that specific approach over others. This demonstrates the architectural maturity they are looking for.

Research the Industry

You don't need to be an insurance expert, but knowing the basics of brokerage and risk management will help you speak the language of your interviewers.

USI values stability

Be prepared to discuss your career progression and why you are looking for a long-term fit at the company.

Questions & practice

Explain the difference between an interface and an abstract class in C#.

Medium · Technical & Coding

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. 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 does the Entity Framework handle database migrations?

Medium · Technical & Coding

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. 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 lifecycle of an ASP.NET request.

Medium · Technical & Coding

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. 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?

What is the difference between a List and an Array in terms of memory and performance?

Medium · Technical & Coding

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. 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?

What are the different types of joins in SQL, and when would you use each?

Medium · Technical & Coding

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. 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?

Replace offset paging on the resource feed with keyset

Easy · keyset pagination · composite index · sort order

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

1. 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.
2. 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.
3. 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.
4. 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?

How would you design a distributed caching system for a high-traffic web application?

Medium · System Design & Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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?

What are the pros and cons of a Microservices architecture versus a Monolithic one?

Medium · System Design & Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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?

How do you ensure your database remains performant as the data grows into the terabytes?

Medium · System Design & Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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?

Describe how you would implement a secure single sign-on (SSO) solution for multiple internal applications.

Medium · System Design & Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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?

Read latency spikes on a sixty-second sawtooth

Medium · cache stampede · single-flight · ttl

The cached listing read path serves about 14k reads/second at an 85% hit rate. p99 sits at 35 ms for 57 seconds, jumps to 900 ms for 3, and repeats. During each spike the primary shows several hundred identical listing queries starting within the same millisecond, all carrying one large tenant's id. Cache entries use a 60-second TTL. Give the mechanism, the ordered checks, the fix, and the correctness hazard your fix must not introduce.

Approach

1. Match the period to a configured number before theorising about load. A spike every 60 seconds against a 60-second TTL is an entry expiring, and you confirm it by correlating spike timestamps with the entry's write time rather than with the traffic curve. If the period had matched a cron or a GC interval instead, this is a different investigation.
2. Establish the concurrency of the miss. Several hundred identical queries in one millisecond means the miss path has no coalescing: every request that arrives between expiry and repopulation recomputes. The herd size is that key's arrival rate times its recompute time, so at 1.2k reads/second for the hot key and a 250 ms recompute you expect about 300 concurrent misses, which matches what is observed.
3. Add single-flight on the miss path so one caller per key recomputes under a short-lived lock while the rest wait for its result. Prefer stale-while-revalidate where the read tolerates it: return the expired value immediately and refresh asynchronously, which removes the latency spike rather than serialising it into a queue of waiters.
4. De-synchronise the keys. Write TTLs with jitter, for example 60 seconds plus or minus 10%, so a deploy or a mass invalidation does not align every key on the same second and turn a per-key herd into a fleet-wide one.

Follow-up

• The same sawtooth appears on a key that is invalidated on write rather than expired. Is that the same bug?
• How does your answer change if the recompute takes 4 seconds instead of 250 ms?

Suggested practice checklist

Built from the rounds and topics USI Insurance Services candidates report.

Day 1 — Map the USI Insurance Services loop

• Write out the reported sequence: Recruiter Screen, Technical/Hiring Manager Screen, Final Panel.
• 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.

Day 2 — Work Software Engineering

• Spend the session on Software Engineering, which USI Insurance Services candidates report being tested on.
• Write one worked example in Software Engineering and time yourself on it.

Deliverable: One timed worked example in Software Engineering.

Day 3 — Work BI Development

• Spend the session on BI Development, which USI Insurance Services candidates report being tested on.
• Write one worked example in BI Development and time yourself on it.

Deliverable: One timed worked example in BI Development.

Day 4 — Work Lead Software Architecture

• Spend the session on Lead Software Architecture, which USI Insurance Services candidates report being tested on.
• Write one worked example in Lead Software Architecture and time yourself on it.

Deliverable: One timed worked example in Lead Software Architecture.

Day 5 — Answer out loud: Technical & Coding

• Answer aloud, timed: Explain the difference between an interface and an abstract class in C#.
• Answer aloud, timed: What are the different types of joins in SQL, and when would you use each?

Deliverable: Spoken answers to 2 reported Technical & Coding question(s), under time.

Day 6 — Answer out loud: System Design & Architecture

• Answer aloud, timed: How would you design a distributed caching system for a high-traffic web application?
• Answer aloud, timed: What are the pros and cons of a Microservices architecture versus a Monolithic one?

Deliverable: Spoken answers to 2 reported System Design & Architecture question(s), under time.

Day 7 — Answer out loud: Behavioral & Experience

• Answer aloud, timed: Describe a time you had a conflict with a teammate. How did you resolve it?
• Answer aloud, timed: Tell me about a project that failed. What did you learn from the experience?

Deliverable: Spoken answers to 2 reported Behavioral & Experience question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Describe a time you had a conflict with a teammate. How did you resolve it?

Medium · Behavioral & Experience

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. 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 that failed. What did you learn from the experience?

Medium · Behavioral & Experience

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. 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 a situation where a stakeholder provides vague or conflicting requirements?

Medium · Behavioral & Experience

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. 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?

Walk me through your process for performing a code review. What are you looking for?

Medium · Behavioral & Experience

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. 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?