A Software Engineer at OWKIN plays a pivotal role in developing innovative solutions that harness the power of data science and artificial intelligence to revolutionize healthcare. This position is critical as it directly impacts the creation and implementation of bioinformatics pipelines and machine learning models, enabling researchers and healthcare professionals to derive insightful conclusions from complex datasets. As part of a team dedicated to advancing medical research, you will contribute to projects that can potentially transform patient care and treatment outcomes. In this role, you will work collaboratively with data scientists, product managers, and other engineers to design software solutions that are not only effective but also scalable and maintainable. You'll be engaged in various problem spaces, from building robust APIs to developing machine learning algorithms, thus ensuring that OWKIN remains at the forefront of technological advancements in the life sciences sector. Expect to encounter complex challenges that require both technical expertise and innovative thinking, making this position both exciting and rewarding.
Phone Screening
reportedInitial call with HR to discuss your background and alignment with the role.
What to demonstrate
- Initial call with HR to discuss your background and alignment with the role
- Depth in Pipeline Engineering
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 Discussion
reportedDiscussion with a team lead focusing on your technical skills and experience.
What to demonstrate
- Discussion with a team lead focusing on your technical skills and experience
- Depth in Pipeline Engineering
How to prepare
- Answer aloud and timed: Can you discuss a recent project where you utilized machine learning techniques?
- Answer aloud and timed: Describe how you would optimize a slow-running algorithm.
Technical Assessment
reportedComplete a technical assessment at home to showcase coding and problem-solving skills.
What to demonstrate
- Complete a technical assessment at home to showcase coding and problem-solving skills
- Depth in Pipeline Engineering
How to prepare
- Answer aloud and timed: What programming languages are you proficient in, and how have you applied them?
- Answer aloud and timed: How would you design a system for real-time data processing?
Debrief Session
reportedPresent your technical assessment solution to a technical lead and answer questions.
What to demonstrate
- Present your technical assessment solution to a technical lead and answer questions
- Depth in Pipeline Engineering
How to prepare
- Answer aloud and timed: Discuss the trade-offs between microservices and monolithic architectures.
- Answer aloud and timed: What considerations would you keep in mind while designing a RESTful API?
Collaborative Discussions
reportedEngage in discussions with data scientists and project managers to assess communication skills.
What to demonstrate
- Engage in discussions with data scientists and project managers to assess communication skills
- Depth in Pipeline Engineering
How to prepare
- Answer aloud and timed: How do you ensure high availability and fault tolerance in your applications?
- Answer aloud and timed: Describe a time you had to refactor a legacy system. What was your approach?
PracHub editorial advice for the preparation topics above.
Prepare for Technical Assessments
Practice coding challenges and review algorithms to build confidence. Familiarity with common data structures will also be beneficial.
Understand OWKIN’s Mission
Research the company's projects and values to articulate how your goals align with theirs during interviews.
Engage with Interviewers
Be ready to ask thoughtful questions during interviews, demonstrating your interest and enthusiasm for the role.
Show Your Problem-Solving Approach
When discussing past experiences, focus on your thought process and how you arrived at solutions. This showcases your analytical skills.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Describe how you would optimize a slow-running algorithm.
Describe how you would optimize a slow-running algorithm.
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?
Write a function to find the longest substring without repeating characters.
Write a function to find the longest substring without repeating characters.
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 your solution to the "two-sum problem" and discuss its time complexity.
Explain your solution to the "two-sum problem" and discuss its time complexity.
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 in your preferred language?
How would you implement a binary search algorithm in your preferred 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?
Discuss the advantages of using hash maps over arrays for certain problems.
Discuss the advantages of using hash maps over arrays for certain problems.
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 a problem involving tree traversal and explain your thought process.
Solve a problem involving tree traversal and explain your thought process.
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?
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?
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?
Explain the difference between supervised and unsupervised learning.
Explain the difference between supervised and unsupervised learning.
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?
What is a bioinformatics pipeline, and how does it function?
What is a bioinformatics pipeline, and how does it function?
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 discuss a recent project where you utilized machine learning techniques?
Can you discuss a recent project where you utilized machine learning techniques?
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?
What programming languages are you proficient in, and how have you applied them?
What programming languages are you proficient in, and how have you applied them?
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 design a system for real-time data processing?
How would you design a system for real-time data processing?
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?
Discuss the trade-offs between microservices and monolithic architectures.
Discuss the trade-offs between microservices and monolithic architectures.
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?
What considerations would you keep in mind while designing a RESTful API?
What considerations would you keep in mind while designing a RESTful API?
Approach
- Say who the caller is and what they do when the call fails halfway.
- Define the identity of a request so a retry cannot double-apply it.
- Separate accepted, pending, failed and confirmed; they are different facts.
- 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?
How do you ensure high availability and fault tolerance in your applications?
How do you ensure high availability and fault tolerance in your applications?
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 dataset with incomplete entries, how would you approach data cleaning?
Given a dataset with incomplete entries, how would you approach data cleaning?
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 performance issue in a production environment?
How would you handle a performance issue in a production environment?
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 tasked with improving a product feature based on user feedback, what steps would you take?
If tasked with improving a product feature based on user feedback, 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 evaluate the success of a new feature after its launch?
How would you evaluate the success of a new feature after its launch?
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 method for debugging a complex software issue.
Describe your method for debugging a complex software issue.
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 OWKIN candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the OWKIN loop
- Write out the reported sequence: Phone Screening, Technical Discussion, Technical Assessment, Debrief Session, Collaborative 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 5 reported rounds, with the weakest marked.
02Work Pipeline Engineering
- Spend the session on Pipeline Engineering, which OWKIN candidates report being tested on.
- Write one worked example in Pipeline Engineering and time yourself on it.
Deliverable: One timed worked example in Pipeline Engineering.
03Work Technical Interview Preparation
- Spend the session on Technical Interview Preparation, which OWKIN candidates report being tested on.
- Write one worked example in Technical Interview Preparation and time yourself on it.
Deliverable: One timed worked example in Technical Interview Preparation.
04Work Bioinformatics Domain Knowledge
- Spend the session on Bioinformatics Domain Knowledge, which OWKIN candidates report being tested on.
- Write one worked example in Bioinformatics Domain Knowledge and time yourself on it.
Deliverable: One timed worked example in Bioinformatics Domain Knowledge.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: Explain the difference between supervised and unsupervised learning.
- Answer aloud, timed: What is a bioinformatics pipeline, and how does it function?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: System Design / Architecture
- Answer aloud, timed: How would you design a system for real-time data processing?
- Answer aloud, timed: Discuss the trade-offs between microservices and monolithic architectures.
Deliverable: Spoken answers to 2 reported System Design / Architecture question(s), under time.
07Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Describe a challenging project you worked on and how you overcame obstacles.
- Answer aloud, timed: How do you prioritize your tasks when working on multiple projects?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership 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.
Describe a time you had to refactor a legacy system. What was your approach?
Describe a time you had to refactor a legacy system. What was your approach?
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 challenging project you worked on and how you overcame obstacles.
Describe a challenging project you worked on and how you overcame obstacles.
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?
Can you provide an example of how you handled conflict within a team?
Can you provide an example of how you handled conflict within a team?
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?
What motivates you to perform at your best?
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 approach feedback and criticism from peers?
How do you approach feedback and criticism from peers?
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
Describe a time you had to refactor a legacy system. What was your approach?
- 02
Describe a challenging project you worked on and how you overcame obstacles.
- 03
How do you prioritize your tasks when working on multiple projects?
- 04
Can you provide an example of how you handled conflict within a team?
What is the typical interview difficulty at OWKIN?
The interview difficulty is generally considered average, with a mix of technical and behavioral questions. Adequate preparation can significantly enhance your chances of success.
OWKIN Software Engineer candidate reports ↗How long does the interview process usually take?
The entire interview process can take a few weeks, depending on scheduling and the number of candidates being interviewed. Candidates should be prepared for multiple rounds.
OWKIN Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates typically demonstrate a strong technical foundation, effective communication skills, and a collaborative mindset. They are also adaptable and show a genuine interest in the company's mission.
OWKIN Software Engineer candidate reports ↗What is the company culture like at OWKIN?
OWKIN fosters a collaborative and innovative culture, encouraging employees to contribute ideas and work together towards common goals. The team values diversity and a commitment to improving healthcare through technology.
OWKIN Software Engineer candidate reports ↗Are there opportunities for remote work?
OWKIN supports a hybrid work environment, allowing for flexibility in work arrangements. Candidates should inquire about specific policies during the interview process.
OWKIN Software Engineer candidate reports ↗What topics does OWKIN test in interviews?
OWKIN interviews most often cover Stakeholder Communication, Incident Management, Stakeholder Management, Root Cause Analysis (RCA), and Performance Tuning. The exact emphasis depends on the specific role you apply for.
OWKIN 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.
- 01OWKIN 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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