As a Software Engineer at Janus Henderson Investors, you play a pivotal role in developing and maintaining the technology solutions that drive the firm's investment strategies and operations. This position is integral to ensuring that our products not only meet the high standards expected by our clients but also effectively support the complex financial instruments and services we offer. Your work will directly impact the efficiency and functionality of our software systems, which are critical to the investment management process. In this role, you will collaborate with cross-functional teams, including product managers, data scientists, and other engineers, to create scalable, robust applications that enhance user experience and operational efficiency. You will be involved in various projects, from optimizing existing platforms to developing new features and integrations that align with our strategic goals. The complexity and scale of the systems you will work on provide an exciting challenge and the opportunity to make a significant impact within the organization.
Phone Screening
reportedInitial screening call to assess candidate's background and fit for the role.
What to demonstrate
- Initial screening call to assess candidate's background and fit for the role
- Depth in Platform Engineering (Role Domain)
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 Assessments
reportedInterviews that evaluate technical skills through problem-solving tasks.
What to demonstrate
- Interviews that evaluate technical skills through problem-solving tasks
- Depth in Platform Engineering (Role Domain)
How to prepare
- Answer aloud and timed: Describe a challenging technical problem you faced and how you resolved it.
- Answer aloud and timed: How do you ensure code quality and maintainability in your projects?
Behavioral Interviews
reportedDiscussions focusing on past experiences and cultural fit within the team.
What to demonstrate
- Discussions focusing on past experiences and cultural fit within the team
- Depth in Platform Engineering (Role Domain)
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 interviews above and write down what you would ask to confirm before it.
Hiring Manager Discussion
reportedFinal discussions with hiring managers to assess overall fit and expectations.
What to demonstrate
- Final discussions with hiring managers to assess overall fit and expectations
- Depth in Platform Engineering (Role Domain)
How to prepare
- Prepare two projects you led end to end, each with the decision you owned and what it cost.
- Have three questions about the team's roadmap and how success is measured in the first six months.
PracHub editorial advice for the preparation topics above.
Prepare for behavioral questions
Reflect on past experiences and be ready to discuss them in detail; use the STAR method (Situation, Task, Action, Result) to structure your responses.
Showcase your passion for technology
Be ready to discuss personal projects or technologies you are excited about; this demonstrates your commitment to continuous learning and improvement.
Engage with your interviewers
Treat interviews as a two-way conversation; ask insightful questions to learn about the team and company culture.
Practice coding challenges
Utilize online platforms to practice common coding problems and algorithms to enhance your skills.
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. What is the time complexity of your solution?
Write a function to reverse a string. What is the time complexity of your solution?
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 implement a binary search algorithm? Can you explain it step by step?
How would you implement a binary search algorithm? Can you explain it step by step?
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?
Given a list of integers, write a function to find the two numbers that add up to a specific target.
Given a list of integers, write a function to find the two numbers that add up to a specific target.
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?
Explain the concept of recursion and provide an example of when you would use it.
Explain the concept of recursion and provide an example of when you would use it.
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 trade-offs of using different data structures for a particular application.
Discuss the trade-offs of using different data structures for a particular 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?
Hold a per-tenant active cap against concurrent creates
A tenant on the standard plan may hold at most 50 resources with status='active'. The create handler runs SELECT count(*) FROM resource WHERE tenant_id = $1 AND status = 'active', compares to 50, then inserts. Two creates arrive 3 ms apart on different instances and the tenant lands at 51. Name the anomaly, say whether PostgreSQL 16 READ COMMITTED or REPEATABLE READ prevents it and why, then give an implementation that holds the cap at READ COMMITTED with the exact statements. Finally, say what changes when the cap is 'at most one running export per tenant' on job_run.
Approach
- Name it: write skew. The two transactions read an overlapping set and write disjoint rows, so there is no row-level conflict for the engine to detect and each commit is individually legal.
- Rule out the levels precisely. READ COMMITTED takes a fresh snapshot per statement and takes no lock on the counted rows, so both see 49. PostgreSQL's REPEATABLE READ is snapshot isolation: it removes non-repeatable reads and phantoms within the snapshot but still admits write skew, because the anomaly is not a re-read of a changed row, it is a read of a set that a concurrent transaction invalidates. Only SERIALIZABLE closes it, by tracking the read dependency and aborting one transaction with SQLSTATE 40001 — a guarantee that exists only if the application re-runs the whole transaction from the read.
- Convert the set predicate into a single-row conflict: keep tenant.active_resource_count and run UPDATE tenant SET active_resource_count = active_resource_count + 1 WHERE tenant_id = $1 AND active_resource_count < 50 in the same transaction as the INSERT. Zero affected rows is the cap, returned as 409. The row lock serialises the decision at any isolation level, and contention is bounded to one tenant's row — which is also the fair-scheduling unit, unlike a global counter that would convoy every tenant behind one row.
- State the cost you just took on: a counter is a second source of truth that can drift, so every path that changes status must adjust it inside the same transaction, and a periodic reconciliation has to exist, with resource_revision as the authority for what the count should have been.
Follow-up
- A resource moves from archived back to active. Which statements change, and what breaks if the counter update and the status change land in different transactions?
- The cap becomes plan-dependent and a plan can change mid-month. Where does the number 50 live, and who reads it?
Explain why the owner filter ignores the listing index
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
- 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.
- 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.
- 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.
- 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?
What programming languages are you most proficient in, and how have you applied them in previous projects?
What programming languages are you most proficient in, and how have you applied them in previous projects?
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?
Can you explain the difference between object-oriented and functional programming?
Can you explain the difference between object-oriented and functional programming?
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 a challenging technical problem you faced and how you resolved it.
Describe a challenging technical problem you faced and how you resolved it.
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 ensure code quality and maintainability in your projects?
How do you ensure code quality and maintainability in your projects?
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?
Given a hypothetical scenario where a system is experiencing performance issues, what steps would you take to
Given a hypothetical scenario where a system is experiencing performance issues, what steps would you take to identify and resolve the problem?
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 designing a new feature from concept to implementation.
Describe your process for designing a new feature from concept to implementation.
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 balance technical debt with feature development in a project?
How would you balance technical debt with feature development in a project?
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?
Provide an example of how you have made a decision based on data analysis.
Provide an example of how you have made a decision based on data analysis.
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 approach debugging a complex issue in a production environment?
How would you approach debugging a complex issue in 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 Janus Henderson Investors candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Janus Henderson Investors loop
- Write out the reported sequence: Phone Screening, Technical Assessments, Behavioral Interviews, Hiring Manager Discussion.
- 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 4 reported rounds, with the weakest marked.
02Work Platform Engineering (Role Domain)
- Spend the session on Platform Engineering (Role Domain), which Janus Henderson Investors candidates report being tested on.
- Write one worked example in Platform Engineering (Role Domain) and time yourself on it.
Deliverable: One timed worked example in Platform Engineering (Role Domain).
03Work Cloud COE (Center of Excellence)
- Spend the session on Cloud COE (Center of Excellence), which Janus Henderson Investors candidates report being tested on.
- Write one worked example in Cloud COE (Center of Excellence) and time yourself on it.
Deliverable: One timed worked example in Cloud COE (Center of Excellence).
04Work Endpoint Platform Engineering
- Spend the session on Endpoint Platform Engineering, which Janus Henderson Investors candidates report being tested on.
- Write one worked example in Endpoint Platform Engineering and time yourself on it.
Deliverable: One timed worked example in Endpoint Platform Engineering.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: What programming languages are you most proficient in, and how have you applied them in previous projects?
- Answer aloud, timed: Can you explain the difference between object-oriented and functional programming?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Describe a time when you had to collaborate with a difficult team member. How did you handle the situation?
- Answer aloud, timed: Can you give an example of a project where you took the lead? What was the outcome?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.
07Answer out loud: Problem-Solving / Case Studies
- Answer aloud, timed: How would you approach debugging a complex issue in a production environment?
- Answer aloud, timed: Given a hypothetical scenario where a system is experiencing performance issues, what steps would you take to identify and resolve the problem?
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.
Discuss your experience with version control systems like Git.
Discuss your experience with version control systems like Git.
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 when you had to collaborate with a difficult team member. How did you handle the situation?
Describe a time when you had to collaborate with a difficult team member. How did you handle the situation?
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 give an example of a project where you took the lead? What was the outcome?
Can you give an example of a project where you took the lead? What was the outcome?
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 working on multiple projects?
How do you prioritize your 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?
Discuss a time when you received constructive criticism. How did you respond?
Discuss a time when you received constructive criticism. How did you respond?
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 to perform at your best in a team setting?
What motivates you to perform at your best in a team setting?
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
Discuss your experience with version control systems like Git.
- 02
Describe a time when you had to collaborate with a difficult team member. How did you handle the situation?
- 03
Can you give an example of a project where you took the lead? What was the outcome?
- 04
How do you prioritize your tasks when working on multiple projects?
What is the interview difficulty and how much preparation time is typical?
The interview difficulty is generally classified as average, with candidates typically spending several weeks preparing. Focus on understanding both technical and behavioral aspects of the role.
Janus Henderson Investors Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates demonstrate a strong technical foundation, effective communication skills, and a genuine interest in the company's mission and values. Being able to articulate past experiences clearly is crucial.
Janus Henderson Investors Software Engineer candidate reports ↗What is the culture and working style at Janus Henderson Investors?
The culture emphasizes collaboration, respect, and continuous improvement. Engineers are encouraged to share ideas and innovate within their teams.
Janus Henderson Investors Software Engineer candidate reports ↗What is the typical timeline from the initial screen to the offer?
The interview process can take several weeks, with candidates often receiving feedback within a few days after each interview stage.
Janus Henderson Investors Software Engineer candidate reports ↗Are there remote work or hybrid expectations?
While some positions may offer flexibility, it's essential to confirm specific arrangements during the interview process, as they can vary by team and role.
Janus Henderson Investors Software Engineer candidate reports ↗What topics does Janus Henderson Investors test in interviews?
Janus Henderson Investors interviews most often cover SQL, Python, Presentation Skills, Behavioral Interviewing, and Data Engineering. The exact emphasis depends on the specific role you apply for.
Janus Henderson Investors 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.
- 01Janus Henderson Investors 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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