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UKG Software Engineer Interview Guide

UKG Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

At UKG (Ultimate Kronos Group), our purpose is people. As a Software Engineer, you will play a critical role in building, scaling, and maintaining our world-class Human Capital Management (HCM) and workforce management cloud solutions. Our products, such as UKG Pro, UKG Ready, and UKG Dimensions, serve tens of millions of users worldwide, making high availability, security, and performance the core pillars of our engineering efforts. You will work in a highly collaborative, cross-functional environment alongside product managers, UX designers, QA engineers, and site reliability teams. The engineering organization at UKG is currently driving massive technical initiatives, including transitioning legacy systems into microservices architectures, optimizing high-throughput database operations, and leveraging cloud-native technologies.

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

Focus areas

  • Data Structures (DSA)
  • Object-Oriented Programming (OOP)
  • Algorithms

The UKG interview process

UKG candidates report 7 rounds over 4-6 weeks. The stages below are what candidates describe, not a published process.

Automated Online Assessment

Initial assessment testing core computer science fundamentals and algorithmic coding.

What to demonstrate

  • Initial assessment testing core computer science fundamentals and algorithmic coding
  • Depth in Data Structures (DSA)

How to prepare

  • Answer aloud and timed: Write a function to minimize the sum of an array after applying a set of division operations.
  • Answer aloud and timed: Given two sorted arrays, find the median of the combined sorted arrays in logarithmic time.

Recruiter Screen

Discussion with a recruiter to review your background and fit for the role.

What to demonstrate

  • Discussion with a recruiter to review your background and fit for the role
  • Depth in Data Structures (DSA)

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 Interviews

Series of interviews focusing on technical skills and practical experience.

What to demonstrate

  • Series of interviews focusing on technical skills and practical experience
  • Depth in Data Structures (DSA)

How to prepare

  • Answer aloud and timed: Given a binary tree, write a function to determine if a path from the root to any leaf node equals a target sum.
  • Answer aloud and timed: Explain the SOLID principles, with a specific focus on how the Liskov Substitution Principle is applied or violated in software design.

Managerial Interviews

Interviews that assess managerial skills and cultural fit within the team.

What to demonstrate

  • Interviews that assess managerial skills and cultural fit within the team
  • Depth in Data Structures (DSA)

How to prepare

  • Answer aloud and timed: Implement a Factory Method design pattern to handle generating different report formats, such as PDF and Word documents.
  • Answer aloud and timed: Design the class structure and object relationships for a simplified stock trading application.

System Architecture Deep Dive

In-depth discussion on system architecture relevant to the role.

What to demonstrate

  • In-depth discussion on system architecture relevant to the role
  • Depth in Data Structures (DSA)

How to prepare

  • Answer aloud and timed: Describe the internal working of a hash map, focusing on collision resolution and time complexity.
  • Answer aloud and timed: What is the difference between a fail-fast and a fail-safe iterator in Java?

Live Programming Exercises

Hands-on coding exercises to demonstrate your programming skills.

What to demonstrate

  • Hands-on coding exercises to demonstrate your programming skills
  • Depth in Data Structures (DSA)

How to prepare

  • Answer aloud and timed: Explain the bean initialization lifecycle in Spring Boot and the differences between singleton and prototype scopes.
  • Answer aloud and timed: How do you handle circular dependencies between beans in a Spring application?

Behavioral Discussions

Conversations with senior engineering leadership focusing on behavioral aspects.

What to demonstrate

  • Conversations with senior engineering leadership focusing on behavioral aspects
  • Depth in Data Structures (DSA)

How to prepare

  • Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
  • Re-read the description of the behavioral discussions above and write down what you would ask to confirm before it.

Where candidates lose points

Know Your Resume Inside Out

UKG interviewers frequently conduct deep resume reviews. Be ready to explain every technology, tool, and project you have listed, including the architectural decisions and trade-offs involved.

If you list a tool or technology on your resume, expect to be questioned on it

Ensure you can explain why you chose it and how it works under the hood.

Clarify the Role Title Upfront

To ensure alignment, confirm the exact scope, expectations, and title of the position with your recruiter early in the process. This helps prevent any late-stage misalignment regarding seniority.

Questions & practice

Write a function to minimize the sum of an array after applying a set of division operations.

Medium · Data Structures & Algorithms (DSA)

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 two sorted arrays, find the median of the combined sorted arrays in logarithmic time.

Medium · Data Structures & Algorithms (DSA)

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?

Determine if two strings are valid anagrams of each other.

Medium · Data Structures & Algorithms (DSA)

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?

Implement an algorithm to generate all combinations of well-formed parentheses for a given number of pairs.

Medium · Data Structures & Algorithms (DSA)

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 binary tree, write a function to determine if a path from the root to any leaf node equals a target su

Medium · Data Structures & Algorithms (DSA)

Given a binary tree, write a function to determine if a path from the root to any leaf node equals a target sum.

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 internal working of a hash map, focusing on collision resolution and time complexity.

Medium · Object-Oriented Programming & Design (OO

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 garbage collection work in Java, and what is the purpose of the Metaspace?

Medium · Databases & Core CS Fundamentals

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?

Write an SQL query to retrieve the top five employees with the highest salaries from a database schema.

Medium · Databases & Core CS Fundamentals

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 database normalization and explain when you would intentionally denormalize a database.

Medium · Databases & Core CS Fundamentals

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?

Explain the SOLID principles, with a specific focus on how the Liskov Substitution Principle is applied or vio

Medium · Object-Oriented Programming & Design (OO

Explain the SOLID principles, with a specific focus on how the Liskov Substitution Principle is applied or violated in software design.

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?

Implement a Factory Method design pattern to handle generating different report formats, such as PDF and Word

Medium · Object-Oriented Programming & Design (OO

Implement a Factory Method design pattern to handle generating different report formats, such as PDF and Word documents.

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?

Design the class structure and object relationships for a simplified stock trading application.

Medium · Object-Oriented Programming & Design (OO

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 is the difference between a fail-fast and a fail-safe iterator in Java?

Medium · Object-Oriented Programming & Design (OO

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?

Explain the bean initialization lifecycle in Spring Boot and the differences between singleton and prototype s

Medium · Backend Frameworks & Architecture

Explain the bean initialization lifecycle in Spring Boot and the differences between singleton and prototype scopes.

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 to implement a secure, JWT-based authentication and authorization flow in a microservices environ

Medium · Backend Frameworks & Architecture

Describe how to implement a secure, JWT-based authentication and authorization flow in a microservices environment.

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 strategies would you use to implement rate limiting and throttling at the API gateway level?

Medium · Backend Frameworks & Architecture

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. 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?

Explain the concept of fault tolerance in microservices and how you would configure a circuit breaker.

Medium · Backend Frameworks & 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 structural and performance differences between Red-Black trees and AVL trees?

Medium · Databases & Core CS Fundamentals

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?

Explain the difference between HTTP GET and POST methods, specifically focusing on idempotency.

Medium · Databases & Core CS Fundamentals

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. 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?

Walk me through the architecture of your most recent project and explain the technical trade-offs you made.

Medium · Behavioral & Project Discussion

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?

One log partition stops advancing while the others drain

Easy · poison message · head-of-line blocking · consumer lag

Search results for a subset of tenants are hours stale; the rest are current. The projection consumer reports lag of zero on 15 of 16 partitions and 400,000 on one. Its error rate is flat and its CPU is idle. outbox_event has no pending rows older than a second, so the relay has published everything it holds. Identify the mechanism, give the ordered checks, and state what you do in the first ten minutes versus what you change permanently.

Approach

  1. Read the lag distribution first. A slow consumer lags everywhere; zero on fifteen partitions and 400,000 on one is not throughput. Idle CPU on the stuck partition means the consumer is not advancing its offset at all, which points at one message it cannot get past rather than at a rate problem.
  2. Exonerate the producer before touching the consumer. No pending outbox rows older than a second means the relay published, so the event exists in the log. This separates never sent from sent and never applied, which are different code paths and usually different owners.
  3. Read the message at the stuck offset and the handler's log lines for its event_id. A flat error rate with no progress has two explanations and you must distinguish them: the handler is throwing and the retry loop is swallowing it, or the handler is blocking on something and never returning. Idle CPU with no error lines favours the second.
  4. Mitigate before diagnosing further. Move the offending event to a dead-letter store and commit the offset past it. Adding consumers does nothing here, because a partition is consumed by exactly one member of the group, and the blast radius is every aggregate hashed to that partition, not only the aggregate that produced the bad event.

Follow-up

  • The dead-lettered event carried aggregate_version 7 and the projection had applied 6. What must the replay do differently if 8 and 9 landed in the meantime?
  • How do you show staleness to the user while the partition is behind, given the API already returns the projection's watermark?

Suggested practice checklist

Built from the rounds and topics UKG candidates report.

Day 1 — Map the UKG loop

  • Write out the reported sequence: Automated Online Assessment, Recruiter Screen, Technical Interviews, Managerial Interviews, System Architecture Deep Dive, Live Programming Exercises.
  • 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 7 reported rounds, with the weakest marked.

Day 2 — Work Data Structures (DSA)

  • Spend the session on Data Structures (DSA), which UKG candidates report being tested on.
  • Write one worked example in Data Structures (DSA) and time yourself on it.

Deliverable: One timed worked example in Data Structures (DSA).

Day 3 — Work Object-Oriented Programming (OOP)

  • Spend the session on Object-Oriented Programming (OOP), which UKG candidates report being tested on.
  • Write one worked example in Object-Oriented Programming (OOP) and time yourself on it.

Deliverable: One timed worked example in Object-Oriented Programming (OOP).

Day 4 — Work Algorithms

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

Deliverable: One timed worked example in Algorithms.

Day 5 — Answer out loud: Data Structures & Algorithms (DSA)

  • Answer aloud, timed: Write a function to minimize the sum of an array after applying a set of division operations.
  • Answer aloud, timed: Given two sorted arrays, find the median of the combined sorted arrays in logarithmic time.

Deliverable: Spoken answers to 2 reported Data Structures & Algorithms (DSA) question(s), under time.

Day 6 — Answer out loud: Object-Oriented Programming & Design (OOP/OOD)

  • Answer aloud, timed: Explain the SOLID principles, with a specific focus on how the Liskov Substitution Principle is applied or violated in software design.
  • Answer aloud, timed: Implement a Factory Method design pattern to handle generating different report formats, such as PDF and Word documents.

Deliverable: Spoken answers to 2 reported Object-Oriented Programming & Design (OOP/OOD) question(s), under time.

Day 7 — Answer out loud: Backend Frameworks & Architecture

  • Answer aloud, timed: Explain the bean initialization lifecycle in Spring Boot and the differences between singleton and prototype scopes.
  • Answer aloud, timed: How do you handle circular dependencies between beans in a Spring application?

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

Behavioural preparation

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

How do you handle circular dependencies between beans in a Spring application?

Medium · Backend Frameworks & Architecture

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 challenging technical conflict you had with a teammate and how you resolved it.

Medium · Behavioral & Project Discussion

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 leverage AI tools or automated workflows to improve your daily development efficiency?

Medium · Behavioral & Project Discussion

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 when a production deployment failed. How did you troubleshoot the issue, and what did you

Medium · Behavioral & Project Discussion

Tell me about a time when a production deployment failed. How did you troubleshoot the issue, and what did you learn?

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?

Why are you interested in joining UKG, and how do you align with our focus on human-centric software?

Medium · Behavioral & Project Discussion

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?