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Employment Hero Software Engineer Interview Guide

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

The 60-second brief

As a Software Engineer at Employment Hero, you are at the heart of an ambitious mission to make employment easier and more rewarding for everyone. You will be responsible for building and scaling robust platforms that manage payroll, benefits, and HR workflows for thousands of businesses globally. Your work directly impacts the financial well-being of users, requiring a blend of technical precision and a deep sense of responsibility toward the end-user experience. This role is critical to the Employment Hero ecosystem because you are not just writing code; you are architecting solutions for high-stakes, high-volume data environments. Whether you are optimizing backend services, refining microservice architecture, or building intuitive features, your contributions dictate the reliability and scalability of the product.

This guide is scoped to a Software Engineer candidate at Employment Hero.

Focus areas

  • URL Shortener System Design
  • PHP
  • Data Structures & Algorithms

The Employment Hero interview process

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

Initial Screening

Initial outreach and screening to assess candidate qualifications.

What to demonstrate

  • Initial outreach and screening to assess candidate qualifications
  • Depth in URL Shortener System Design

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

Evaluation through take-home assignments or live coding to test technical skills.

What to demonstrate

  • Evaluation through take-home assignments or live coding to test technical skills
  • Depth in URL Shortener System Design

How to prepare

  • Answer aloud and timed: Implement a file searching function.
  • Answer aloud and timed: Explain your approach to solving specific LeetCode-style data structure and algorithm problems.

Final Round Discussions

Conversations with engineering leadership focusing on technical and behavioral aspects.

What to demonstrate

  • Conversations with engineering leadership focusing on technical and behavioral aspects
  • Depth in URL Shortener System Design

How to prepare

  • Answer aloud and timed: Design a URL Shortener service (similar to bit.ly).
  • Answer aloud and timed: Design a hotel reservation system.

Where candidates lose points

Structure your answers

Use the STAR method (Situation, Task, Action, Result) for behavioral questions to keep your responses concise and impactful.

Clarify before coding

During live coding, always ask clarifying questions about the requirements. This demonstrates that you think about edge cases before writing code.

Be ready for feedback

Interviewers may ask you to optimize your code or change your design. Stay calm and treat these as a collaborative conversation rather than a critique.

Know your resume

Be prepared to discuss every project listed on your resume in detail, including the specific technologies used and the challenges you faced.

Questions & practice

Implement a pattern generator that takes character inputs and shape types, requiring the use of OOP principles

Medium · Technical & Coding Proficiency

Implement a pattern generator that takes character inputs and shape types, requiring the use of OOP principles like base classes and subclasses.

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?

Solve medium-level algorithmic problems (e.g., House Robber).

Medium · Technical & Coding Proficiency

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 a file searching function.

Medium · Technical & Coding Proficiency

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?

Explain your approach to solving specific LeetCode-style data structure and algorithm problems.

Medium · Technical & Coding Proficiency

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?

Explain how you would structure a database schema for a specific business problem.

Medium · System Design & Architecture

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 why the owner filter ignores the listing index

Medium · composite index · query plans · sort elimination

The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id = $2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.

Approach

  1. Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
  2. For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
  3. Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
  4. Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.

Follow-up

  • 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
  • A dashboard runs this for 40 owners in one page load. What changes about the design?

Design a URL Shortener service (similar to bit.ly).

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?

Design a hotel reservation system.

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?

Design a logging service for a microservice-based system.

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?

Every query on one table stalls for forty seconds mid-deploy

Medium · lock contention · ddl · migrations

During a release on PostgreSQL, every query touching resource times out for about 40 seconds and then recovers with no intervention. The release ran one migration, ALTER TABLE resource ADD COLUMN archived_reason TEXT, and the migration log shows it completing in 6 ms. Unrelated tables showed no change in error rate. Explain how a 6 ms statement caused a 40-second stall, give the ordered checks you would run on a live system to confirm it, and give the migration procedure that prevents a repeat.

Approach

  1. Separate the statement's duration from the lock's duration. ADD COLUMN with no default is a catalogue-only change and genuinely runs in milliseconds, but it requires ACCESS EXCLUSIVE, and it cannot acquire that until every transaction already touching the table has finished.
  2. Account for the queueing, which is the part that surprises people. A lock request that is waiting blocks later requests for conflicting modes behind it rather than letting them overtake, so one long-open transaction holds the DDL and the DDL holds all the traffic. The stall length is set by the longest open transaction, not by the size of the change.
  3. Confirm on a live system in this order: pg_stat_activity for that table ordered by xact_start, looking for the oldest transaction and specifically for state = idle in transaction; then pg_locks where granted = false to find the waiter; then join them on pid to name blocker and blocked. pg_blocking_pids() does that join for you and is the fastest single call.
  4. Prevent rather than merely time it better. Set lock_timeout to a second or two on the migration session so the DDL abandons the queue after a bounded wait and is retried, instead of holding it for as long as the oldest transaction lives. Be exact about what that buys: queries arriving during the wait still queue behind the pending ACCESS EXCLUSIVE request, so each attempt costs them up to one lock_timeout of added latency. The outage goes from 40 seconds to about one second per attempt, not to zero. Also run migrations away from deploy-time peaks, and put a statement timeout and an idle-in-transaction timeout on the analytics role that opens the long transactions.

Follow-up

  • The same release also wants NOT NULL on that column. What is the sequence that gets there without a long lock?
  • Your lock_timeout retry fails ten times in a row because the analytics transaction is always open. What do you change?

Suggested practice checklist

Built from the rounds and topics Employment Hero candidates report.

Day 1 — Map the Employment Hero loop

  • Write out the reported sequence: Initial Screening, Technical Assessment, Final Round Discussions.
  • 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 URL Shortener System Design

  • Spend the session on URL Shortener System Design, which Employment Hero candidates report being tested on.
  • Write one worked example in URL Shortener System Design and time yourself on it.

Deliverable: One timed worked example in URL Shortener System Design.

Day 3 — Work PHP

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

Deliverable: One timed worked example in PHP.

Day 4 — Work Data Structures & Algorithms

  • Spend the session on Data Structures & Algorithms, which Employment Hero candidates report being tested on.
  • Write one worked example in Data Structures & Algorithms and time yourself on it.

Deliverable: One timed worked example in Data Structures & Algorithms.

Day 5 — Answer out loud: Technical & Coding Proficiency

  • Answer aloud, timed: Implement a pattern generator that takes character inputs and shape types, requiring the use of OOP principles like base classes and subclasses.
  • Answer aloud, timed: Solve medium-level algorithmic problems (e.g., House Robber).

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

Day 6 — Answer out loud: System Design & Architecture

  • Answer aloud, timed: Design a URL Shortener service (similar to bit.ly).
  • Answer aloud, timed: Design a hotel reservation system.

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

Day 7 — Answer out loud: Behavioral & Experience

  • Answer aloud, timed: Describe the most challenging task you have overcome and your specific contribution to the solution.
  • Answer aloud, timed: Tell me about your past work experience and the technologies you have used.

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 the most challenging task you have overcome and your specific contribution to the solution.

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 your past work experience and the technologies you have used.

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?

Why are you interested in joining Employment Hero?

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 complex technical trade-offs in your daily work?

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?