As a Software Engineer at Gallagher, you play a vital role in building and maintaining the technological infrastructure that supports a global leader in insurance, risk management, and consulting. Your work directly impacts how internal and external stakeholders interact with complex data, ensuring that the firm remains agile and efficient in a highly regulated, fast-paced industry. You will likely work within cross-functional teams, contributing to the development of robust software solutions that solve real-world problems. Whether you are focusing on backend systems, internal tools, or client-facing applications, your contribution is critical to the firm’s operational excellence. You can expect a professional, collaborative environment where your technical proficiency is balanced with a need for clear communication and an understanding of the business domain.
Initial Screening
reportedAn initial screening to gauge interest and baseline qualifications.
What to demonstrate
- An initial screening to gauge interest and baseline qualifications
- Depth in SQL
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 Deep-Dive
reportedIn-depth technical discussions with hiring managers or architecture teams.
What to demonstrate
- In-depth technical discussions with hiring managers or architecture teams
- Depth in SQL
How to prepare
- Answer aloud and timed: How do you ensure your code is scalable and maintainable?
- Answer aloud and timed: Can you explain the core principles of Object-Oriented Programming (OOP)?
Aptitude Test
reportedPossibility of an early aptitude test covering reasoning, SQL, and programming fundamentals.
What to demonstrate
- Possibility of an early aptitude test covering reasoning, SQL, and programming fundamentals
- Depth in SQL
How to prepare
- Answer aloud and timed: How do you approach database design and SQL query optimization?
- Answer aloud and timed: Can you walk us through a challenging project you worked on and the specific role you played?
PracHub editorial advice for the preparation topics above.
Be transparent about your expectations
If you are in the middle of other processes, be professional about your timeline, but prioritize clarity regarding your requirements and expectations from the start.
Prepare for the aptitude test
If your process includes an aptitude round, brush up on basic logic, SQL queries, and OOP concepts. These are often used as a baseline filter.
Research the firm
Understand the core business of Gallagher. Showing that you understand how your code supports their clients adds significant value to your candidacy.
Clarify the budget
If you have specific salary requirements, ensure these are addressed early in the screening process to avoid misalignment later.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Walk me through your thought process when faced with an ambiguous technical requirement.
Walk me through your thought process when faced with an ambiguous technical requirement.
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 do you approach solving a performance bottleneck in an application?
How do you approach solving a performance bottleneck in an application?
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 a situation where you had to simplify a complex technical concept for a non-technical audience.
Describe a situation where you had to simplify a complex technical concept for a non-technical audience.
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?
What is your strategy for testing and quality assurance during the development lifecycle?
What is your strategy for testing and quality assurance during the development lifecycle?
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 do you approach database design and SQL query optimization?
How do you approach database design and SQL query optimization?
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?
Write the update path that detects a concurrent edit
resource carries version INT NOT NULL DEFAULT 1. resource_revision holds revision_id, resource_id, version, actor_user_id, change_kind, patch JSONB, request_id, created_at with UNIQUE (resource_id, version). outbox_event holds aggregate_type, aggregate_id, aggregate_version, event_type, payload, status. A PUT carries the version the client read. Write the exact statements for the single transaction that applies the edit, records the revision and enqueues 'resource.updated', and give the handler's branch on zero affected rows. Then say what PostgreSQL 16 does under READ COMMITTED when two of these updates hit one row at once.
Approach
- One transaction, three writes, no network call inside it: UPDATE resource SET title = $3, version = version + 1, updated_at = now() WHERE resource_id = $1 AND tenant_id = $4 AND version = $2; then INSERT the resource_revision row at version $2 + 1; then INSERT the outbox_event row at the same aggregate_version. The event goes to a table rather than a broker because no transaction spans both.
- Branch on the affected-row count before doing anything else. Zero has three causes — stale version, wrong tenant, row gone — so re-read once and map to 409 carrying the current version, or 404 for an id outside the caller's tenant, which also stops the endpoint confirming that another tenant's id exists.
- State the engine behaviour instead of assuming it. Under READ COMMITTED the second UPDATE blocks on the row lock, and when the first commits PostgreSQL re-evaluates the WHERE clause against the newly committed row, so the version predicate now fails and the statement reports zero rows. Under REPEATABLE READ the identical collision raises SQLSTATE 40001 instead, so the handler must fold both shapes into one conflict response.
- Keep UNIQUE (resource_id, version) even though the predicate already serialises writers. It is what makes a lost update unwritable if any other path ever reaches the revision table, and it converts a logic bug into 23505 rather than into a silently missing history row.
Follow-up
- A client sends the version it read ten minutes ago and the resource has moved three versions. What is in your 409 so it can resolve the conflict without a full re-fetch?
- Two editors, two disjoint fields, no overlap. Does your answer still refuse the second write, and should it?
How do you ensure your code is scalable and maintainable?
How do you ensure your code is scalable and maintainable?
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?
Can you explain the core principles of Object-Oriented Programming (OOP)?
Can you explain the core principles of Object-Oriented Programming (OOP)?
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 your process for debugging complex issues within a production environment.
Describe your process for debugging complex issues within a production environment.
Approach
- Establish what changed and when, before forming any theory.
- Pick a bisection that eliminates candidates whichever way it turns out.
- Check the instrumentation before believing the symptom.
- Separate the trigger from the cause; the deploy is rarely the bug.
Follow-up
- What would you look at first, and what would it rule out?
- How would you tell a cause from a coincidence here?
Built from the rounds and topics Gallagher candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Gallagher loop
- Write out the reported sequence: Initial Screening, Technical Deep-Dive, Aptitude Test.
- 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 SQL
- Spend the session on SQL, which Gallagher candidates report being tested on.
- Write one worked example in SQL and time yourself on it.
Deliverable: One timed worked example in SQL.
03Work OOP concepts
- Spend the session on OOP concepts, which Gallagher candidates report being tested on.
- Write one worked example in OOP concepts and time yourself on it.
Deliverable: One timed worked example in OOP concepts.
04Work Aptitude testing
- Spend the session on Aptitude testing, which Gallagher candidates report being tested on.
- Write one worked example in Aptitude testing and time yourself on it.
Deliverable: One timed worked example in Aptitude testing.
05Answer out loud: Technical and Domain Knowledge
- Answer aloud, timed: Explain your experience with.NET frameworks and how you have utilized them in previous projects.
- Answer aloud, timed: Describe your process for debugging complex issues within a production environment.
Deliverable: Spoken answers to 2 reported Technical and Domain Knowledge question(s), under time.
06Answer out loud: Behavioral and Culture Fit
- Answer aloud, timed: Can you walk us through a challenging project you worked on and the specific role you played?
- Answer aloud, timed: How do you handle situations where you have a disagreement with a team member or stakeholder?
Deliverable: Spoken answers to 2 reported Behavioral and Culture Fit question(s), under time.
07Answer out loud: Problem Solving and Aptitude
- Answer aloud, timed: Walk me through your thought process when faced with an ambiguous technical requirement.
- Answer aloud, timed: How do you approach solving a performance bottleneck in an application?
Deliverable: Spoken answers to 2 reported Problem Solving and Aptitude 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.
Explain your experience with.NET frameworks and how you have utilized them in previous projects.
Explain your experience with.NET frameworks and how you have utilized them in previous projects.
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?
Can you walk us through a challenging project you worked on and the specific role you played?
Can you walk us through a challenging project you worked on and the specific role you played?
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 you have a disagreement with a team member or stakeholder?
How do you handle situations where you have a disagreement with a team member or stakeholder?
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 working for a global firm like Gallagher?
Why are you interested in working for a global firm like Gallagher?
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 or tool under a tight deadline.
Tell us about a time you had to learn a new technology or tool under a tight deadline.
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 your tasks when managing multiple competing deadlines?
How do you prioritize your tasks when managing multiple competing 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?
- 01
Explain your experience with.NET frameworks and how you have utilized them in previous projects.
- 02
Can you walk us through a challenging project you worked on and the specific role you played?
- 03
How do you handle situations where you have a disagreement with a team member or stakeholder?
- 04
Why are you interested in working for a global firm like Gallagher?
How long should I expect the entire process to take?
The timeline varies, but many candidates report a process lasting between two weeks to one month. Stay proactive in your follow-ups if you do not hear back within the expected timeframe.
Gallagher Software Engineer candidate reports ↗Is the interview process difficult?
Difficulty is subjective, but you should expect a balanced mix of technical aptitude testing and behavioral assessment. The most successful candidates are those who prepare for both technical questions and the ability to articulate their past work.
Gallagher Software Engineer candidate reports ↗What is the company culture like?
Candidates often describe the team as welcoming and professional. The environment is collaborative, and there is a high value placed on clear communication and professional integrity.
Gallagher Software Engineer candidate reports ↗Should I ask questions at the end?
Yes. Use this time to ask about the team’s current tech stack, how they handle deployments, or what the biggest challenges the team is currently facing. It shows genuine interest and engagement.
Gallagher Software Engineer candidate reports ↗What topics does Gallagher test in interviews?
Gallagher interviews most often cover SQL, Stakeholder Management, Insurance domain knowledge, Stakeholder Communication, and Behavioral Interviewing. The exact emphasis depends on the specific role you apply for.
Gallagher 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.
- 01Gallagher 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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