Unum Software Engineer Interview Guide

The 60-second brief

As a Software Engineer at Unum, you play a pivotal role in shaping the technology solutions that empower our clients and enhance our products. This position is crucial to delivering high-quality software that meets the needs of our users and drives the overall success of our business. You will contribute to the development and maintenance of systems that manage insurance and employee benefits, ensuring that our solutions are reliable, efficient, and user-friendly. In this role, you will collaborate with cross-functional teams to tackle complex technical challenges and deliver innovative solutions. Your work will directly impact the user experience and the operational efficiency of our products, allowing Unum to maintain its competitive edge in the insurance industry. You can expect to engage with various technologies and methodologies, making this position both dynamic and rewarding.

This guide is scoped to a Software Engineer candidate at Unum.

Focus areas

• SQL
• JavaScript
• Query Writing / Database Querying

The Unum interview process

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

Phone Screen

Initial phone call to evaluate your background and fit for the role.

What to demonstrate

• Initial phone call to evaluate your background and fit for the role
• 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 Assessment

Assessment may include coding challenges or case studies to evaluate technical skills.

What to demonstrate

• Assessment may include coding challenges or case studies to evaluate technical skills
• Depth in SQL

How to prepare

• Answer aloud and timed: Can you explain how you would optimize a database query?
• Answer aloud and timed: Walk us through your process for debugging a complex application.

Collaborative Interviews

Interviews focusing on real-world scenarios and problem-solving in a collaborative environment.

What to demonstrate

• Interviews focusing on real-world scenarios and problem-solving in a collaborative environment
• Depth in SQL

How to prepare

• Answer aloud and timed: What design patterns do you commonly use, and why?
• Answer aloud and timed: Tell me about a time you had to work under a tight deadline. How did you manage your time?

Where candidates lose points

Showcase your projects

Be prepared to discuss specific projects you have worked on, including challenges faced and solutions implemented. This demonstrates your practical experience.

Align with company values

Familiarize yourself with Unum’s core values and be ready to articulate how your personal and professional ethos aligns with them.

Practice the STAR method

When answering behavioral questions, use the STAR method to structure your responses clearly and effectively.

Ask insightful questions

Prepare thoughtful questions for your interviewers that reflect your understanding of the role and the company, showing your genuine interest in the position.

Questions & practice

Write a function that reverses a string. Explain your approach.

Medium · Coding / Algorithms

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 would you implement a search algorithm? Discuss its time complexity.

Medium · Coding / Algorithms

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?

Given a dataset, how would you identify and handle missing values?

Medium · Coding / Algorithms

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?

Can you explain the differences between stack and queue data structures?

Medium · Coding / Algorithms

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?

Can you explain how you would optimize a database query?

Medium · Technical / Domain Questions

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?

Write a SQL query to join two tables and retrieve specific data.

Medium · Coding / Algorithms

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?

Describe a challenging technical problem you've encountered and how you resolved it.

Medium · Technical / Domain Questions

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. 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 design patterns do you commonly use, and why?

Medium · Technical / Domain Questions

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

If you were tasked with improving the performance of an existing application, what steps would you take?

Medium · Problem-Solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. 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 approach designing a new feature for an existing product?

Medium · Problem-Solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. 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 how you would handle a sudden requirement change during the development phase.

Medium · Problem-Solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. 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 strategies would you implement to ensure code quality and maintainability?

Medium · Problem-Solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Can you explain your approach to testing and validating software?

Medium · Problem-Solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Walk us through your process for debugging a complex application.

Medium · Technical / Domain Questions

Approach

1. Establish what changed and when, before forming any theory.
2. Pick a bisection that eliminates candidates whichever way it turns out.
3. Check the instrumentation before believing the symptom.
4. 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?

Suggested practice checklist

Built from the rounds and topics Unum candidates report.

Day 1 — Map the Unum loop

• Write out the reported sequence: Phone Screen, Technical Assessment, Collaborative 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 3 reported rounds, with the weakest marked.

Day 2 — Work SQL

• Spend the session on SQL, which Unum candidates report being tested on.
• Write one worked example in SQL and time yourself on it.

Deliverable: One timed worked example in SQL.

Day 3 — Work JavaScript

• Spend the session on JavaScript, which Unum candidates report being tested on.
• Write one worked example in JavaScript and time yourself on it.

Deliverable: One timed worked example in JavaScript.

Day 4 — Work Query Writing / Database Querying

• Spend the session on Query Writing / Database Querying, which Unum candidates report being tested on.
• Write one worked example in Query Writing / Database Querying and time yourself on it.

Deliverable: One timed worked example in Query Writing / Database Querying.

Day 5 — Answer out loud: Technical / Domain Questions

• Answer aloud, timed: Describe a challenging technical problem you've encountered and how you resolved it.
• Answer aloud, timed: What is your experience with Java, SQL, or other programming languages relevant to this position?

Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.

Day 6 — Answer out loud: Behavioral / Leadership

• Answer aloud, timed: Tell me about a time you had to work under a tight deadline. How did you manage your time?
• Answer aloud, timed: Describe a situation where you had a conflict with a team member. How did you handle it?

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

Day 7 — Answer out loud: Problem-Solving / Case Studies

• Answer aloud, timed: If you were tasked with improving the performance of an existing application, what steps would you take?
• Answer aloud, timed: How would you approach designing a new feature for an existing product?

Deliverable: Spoken answers to 2 reported Problem-Solving / Case Studies question(s), under time.

Behavioural preparation

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

What is your experience with Java, SQL, or other programming languages relevant to this position?

Medium · Technical / Domain Questions

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 time you had to work under a tight deadline. How did you manage your time?

Medium · Behavioral / Leadership

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?

Describe a situation where you had a conflict with a team member. How did you handle it?

Medium · Behavioral / Leadership

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?

What motivates you to produce your best work?

Medium · Behavioral / Leadership

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 prioritize tasks when working on multiple projects?

Medium · Behavioral / Leadership

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?

Give an example of a time when you took the lead on a project.

Medium · Behavioral / Leadership

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?