As a Software Engineer at Hays, you play a pivotal role in developing and maintaining innovative software solutions that drive the company's success. This position is critical as it directly impacts the efficiency of operations, the integration of technology into business processes, and the overall user experience for clients and candidates alike. You will work within cross-functional teams to design, implement, and optimize software applications that are integral to Hays' mission of enabling organizations to attract and retain talent effectively. In your role, you will engage with complex problem spaces, tackling challenges that range from enhancing existing systems to architecting new solutions. Your contributions will not only affect the immediate product but also shape the strategic direction of technology within the organization. Hays values the perspectives and ideas brought by its software engineers, fostering an environment where innovation thrives and where your input can make a tangible difference.
Initial Screening Call
reportedA call with a recruiter to discuss your background, career goals, and the specifics of the role.
What to demonstrate
- A call with a recruiter to discuss your background, career goals, and the specifics of the role
- Depth in Programming Skills (General)
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
reportedOne or two rounds of interviews with technical team members to assess your technical skills and problem-solving abilities.
What to demonstrate
- One or two rounds of interviews with technical team members to assess your technical skills and problem-solving abilities
- Depth in Programming Skills (General)
How to prepare
- Answer aloud and timed: Can you describe a challenging technical problem you've solved and the approach you took?
- Answer aloud and timed: What is your experience with agile methodologies, and how have you applied them in your projects?
PracHub editorial advice for the preparation topics above.
Prepare real-world examples
Use specific instances from your previous experience to illustrate your skills and problem-solving abilities.
Understand Hays’ culture
Familiarize yourself with the company’s values and mission, and think about how you align with them.
Practice coding
If applicable, spend time reviewing coding problems and algorithms that are relevant to the role.
Engage with your interviewer
Don’t hesitate to ask thoughtful questions during the interview to demonstrate your interest and engagement.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Write a function to reverse a string in [specific programming language].
Write a function to reverse a string in [specific programming language].
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?
Solve this algorithmic problem: [insert problem here].
Solve this algorithmic problem: [insert problem here].
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?
Discuss the time and space complexity of the algorithms you commonly use.
Discuss the time and space complexity of the algorithms you commonly use.
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 writing tests for your code?
How do you approach writing tests for your code?
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 would you optimize a database query for performance?
How would you optimize a database query for performance?
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?
Denormalise tenant onto revisions and backfill it live
resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.
Approach
- Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
- Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
- Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
- Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.
Follow-up
- The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
- How do you verify the backfill actually finished, given rows are still being inserted while it runs?
Can you describe a challenging technical problem you've solved and the approach you took?
Can you describe a challenging technical problem you've solved and the approach you took?
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?
Discuss any experience you have with cloud technologies or microservices architecture.
Discuss any experience you have with cloud technologies or microservices architecture.
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?
Given a software requirement, how would you approach designing a solution?
Given a software requirement, how would you approach designing a solution?
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?
If you were tasked with improving a legacy system, what steps would you take?
If you were tasked with improving a legacy system, what steps would you take?
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?
How would you handle a situation where your project deadline is at risk?
How would you handle a situation where your project deadline is at risk?
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 thought process when encountering an unexpected software bug.
Describe your thought process when encountering an unexpected software bug.
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?
Walk me through how you would implement a new feature from concept to deployment.
Walk me through how you would implement a new feature from concept to deployment.
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?
How do you approach debugging a complex issue in your code?
How do you approach debugging a complex issue in your code?
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 Hays candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Hays loop
- Write out the reported sequence: Initial Screening Call, Technical 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 2 reported rounds, with the weakest marked.
02Work Programming Skills (General)
- Spend the session on Programming Skills (General), which Hays candidates report being tested on.
- Write one worked example in Programming Skills (General) and time yourself on it.
Deliverable: One timed worked example in Programming Skills (General).
03Work Technical Interviewing
- Spend the session on Technical Interviewing, which Hays candidates report being tested on.
- Write one worked example in Technical Interviewing and time yourself on it.
Deliverable: One timed worked example in Technical Interviewing.
04Work Troubleshooting / Debugging
- Spend the session on Troubleshooting / Debugging, which Hays candidates report being tested on.
- Write one worked example in Troubleshooting / Debugging and time yourself on it.
Deliverable: One timed worked example in Troubleshooting / Debugging.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: Explain your experience with [specific programming languages or technologies].
- Answer aloud, timed: How do you approach debugging a complex issue in your code?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Describe a time you faced a significant challenge in a project. How did you overcome it?
- Answer aloud, timed: How do you prioritize tasks when working on multiple projects?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.
07Answer out loud: Problem-Solving / Case Studies
- Answer aloud, timed: Given a software requirement, how would you approach designing a solution?
- Answer aloud, timed: If you were tasked with improving a legacy system, what steps would you take?
Deliverable: Spoken answers to 2 reported Problem-Solving / Case Studies 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 [specific programming languages or technologies].
Explain your experience with [specific programming languages or technologies].
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?
What is your experience with agile methodologies, and how have you applied them in your projects?
What is your experience with agile methodologies, and how have you applied them in your 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?
Describe a time you faced a significant challenge in a project. How did you overcome it?
Describe a time you faced a significant challenge in a project. How did you overcome it?
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 tasks when working on multiple projects?
How do you prioritize tasks when working on multiple 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?
Tell me about a time when you had to collaborate with a difficult team member. How did you handle it?
Tell me about a time when you had to collaborate with a difficult team member. How did you handle it?
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?
What motivates you in your work, and how do you stay engaged during repetitive tasks?
What motivates you in your work, and how do you stay engaged during repetitive tasks?
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 ensure that your work aligns with the goals of your team and the organization?
How do you ensure that your work aligns with the goals of your team and the organization?
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 [specific programming languages or technologies].
- 02
What is your experience with agile methodologies, and how have you applied them in your projects?
- 03
Describe a time you faced a significant challenge in a project. How did you overcome it?
- 04
How do you prioritize tasks when working on multiple projects?
What is the typical interview process for a Software Engineer at Hays?
The interview process usually involves an initial screening call followed by one or more technical interviews. Candidates can expect a mix of behavioral and technical questions, aimed at assessing both skills and cultural fit.
Hays Software Engineer candidate reports ↗How challenging are the interviews?
Interview difficulty can vary, but candidates should be prepared for a rigorous assessment of their technical abilities and problem-solving skills. It is advisable to practice common coding problems and review your past work experiences.
Hays Software Engineer candidate reports ↗What sets Hays apart from other companies?
Hays places a strong emphasis on collaboration and communication within teams. The company values innovation and encourages its engineers to contribute ideas that can improve processes and products.
Hays Software Engineer candidate reports ↗How long does the interview process typically take?
The timeline from initial screening to an offer can range from a few weeks to over a month, depending on scheduling and the number of interview rounds.
Hays Software Engineer candidate reports ↗Are there opportunities for remote or hybrid work?
Hays offers flexible working arrangements, including options for remote or hybrid work depending on the specific role and team dynamics.
Hays Software Engineer candidate reports ↗What topics does Hays test in interviews?
Hays interviews most often cover SQL, Stakeholder Management, Python, Google Cloud Platform (GCP), and Deep Learning. The exact emphasis depends on the specific role you apply for.
Hays 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.
- 01Hays 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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