The Software Engineer at Health Catalyst plays a pivotal role in developing innovative solutions that enhance healthcare delivery and improve patient outcomes. This position is crucial for translating complex healthcare data into actionable insights that empower healthcare providers and organizations to make informed decisions. As a Software Engineer, you will contribute to various products and services that directly impact the healthcare ecosystem, ensuring that they are reliable, scalable, and user-friendly. You will work on a variety of projects, ranging from building robust web applications to developing sophisticated data analytics tools. The complexity of these projects requires not only technical expertise but also a strong understanding of healthcare processes and user needs. This role is not only about coding; it’s about being part of a mission-driven team that strives to make healthcare better through technology. You'll be joining a culture that values collaboration, innovation, and continuous improvement, making your contributions both meaningful and rewarding.
Phone Screen
reportedInitial call conducted by an HR representative to assess background, motivation, and basic technical skills.
What to demonstrate
- Initial call conducted by an HR representative to assess background, motivation, and basic technical skills
- Depth in SQL
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.
Coding Assessment
reportedTake-home coding assignment to showcase programming capabilities.
What to demonstrate
- Take-home coding assignment to showcase programming capabilities
- Depth in SQL
How to prepare
- Answer aloud and timed: Can you write a SQL query to extract data from multiple tables using joins?
- Answer aloud and timed: Describe a time when you faced a challenge in a project. How did you overcome it?
On-site/Virtual Interview
reportedFinal interview stage with multiple rounds focusing on technical and behavioral aspects.
What to demonstrate
- Final interview stage with multiple rounds focusing on technical and behavioral aspects
- Depth in SQL
How to prepare
- Answer aloud and timed: How do you prioritize your tasks when working on multiple projects?
- Answer aloud and timed: What does teamwork mean to you, and how do you foster collaboration?
PracHub editorial advice for the preparation topics above.
Research the Company
Familiarize yourself with Health Catalyst’s products, mission, and values. Understanding the company will help you articulate your fit during the interview.
Practice Coding
Spend time practicing coding problems, particularly in languages and frameworks relevant to the role. Use platforms like LeetCode or HackerRank to sharpen your skills.
Engage with Interviewers
During interviews, ask insightful questions about the team and projects to demonstrate your interest and engagement.
Showcase Your Projects
Be prepared to discuss past projects in detail, especially those that are relevant to healthcare or involve technologies used at Health Catalyst.
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 its time complexity?
Write a function to reverse a string. What is 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 approach optimizing a slow algorithm?
How would you approach optimizing a slow 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?
Merge partitioned event streams into one ordered feed with bounded lateness
The read-model service consumes 64 log partitions carrying about 4,000 events per second in total. Each partition is ordered within itself, but partitions drift by up to 30 seconds, and the activity feed must present a tenant's events in occurred_at order. Produce the merge. State its complexity, the buffer it requires in events and in bytes, what happens when one partition is idle, and what you do with an event that arrives after you have already emitted its position. Payloads average 1 KB.
Approach
- Merge with a min-heap over the 64 partition heads keyed on (occurred_at, event_id): O(log P) per event and O(n log P) overall. The tie-break on event_id is what makes the output deterministic when two partitions carry the same millisecond, which matters because the feed is paginated and a non-deterministic order reorders pages under the reader.
- Emitting the heap head is only correct once every partition has produced everything up to that timestamp, so the emit condition is a watermark: the minimum across partitions of the highest occurred_at seen, less the allowed lateness. Events are held until the watermark passes them, which is what turns individually ordered streams into a jointly ordered one.
- Size the buffer from the lateness rather than guessing: 4,000 events per second times 30 seconds is 120,000 buffered events, and at 1 KB each about 120 MB of heap. That number is the real price of the ordering guarantee and belongs in front of whoever asked for it.
- Handle the idle partition explicitly, because it fails the feed rather than corrupting it: a partition with no traffic never advances its own maximum, so the watermark freezes and output stops entirely. Either every partition emits a periodic idle marker carrying the broker's current time, or the watermark falls back to wall clock for a partition silent beyond a threshold.
Follow-up
- The lateness budget is raised to five minutes. What is the new buffer, and what besides memory changes?
- The consumer restarts. Where does it resume from, and what does the feed look like for the first 30 seconds?
Can you write a SQL query to extract data from multiple tables using joins?
Can you write a SQL query to extract data from multiple tables using joins?
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?
Write the update path that detects a concurrent edit
resource carries version INT NOT NULL DEFAULT 1. resource_revision holds revision_id, resource_id, version, actor_user_id, change_kind, patch JSONB, request_id, created_at with UNIQUE (resource_id, version). outbox_event holds aggregate_type, aggregate_id, aggregate_version, event_type, payload, status. A PUT carries the version the client read. Write the exact statements for the single transaction that applies the edit, records the revision and enqueues 'resource.updated', and give the handler's branch on zero affected rows. Then say what PostgreSQL 16 does under READ COMMITTED when two of these updates hit one row at once.
Approach
- One transaction, three writes, no network call inside it: UPDATE resource SET title = $3, version = version + 1, updated_at = now() WHERE resource_id = $1 AND tenant_id = $4 AND version = $2; then INSERT the resource_revision row at version $2 + 1; then INSERT the outbox_event row at the same aggregate_version. The event goes to a table rather than a broker because no transaction spans both.
- Branch on the affected-row count before doing anything else. Zero has three causes — stale version, wrong tenant, row gone — so re-read once and map to 409 carrying the current version, or 404 for an id outside the caller's tenant, which also stops the endpoint confirming that another tenant's id exists.
- State the engine behaviour instead of assuming it. Under READ COMMITTED the second UPDATE blocks on the row lock, and when the first commits PostgreSQL re-evaluates the WHERE clause against the newly committed row, so the version predicate now fails and the statement reports zero rows. Under REPEATABLE READ the identical collision raises SQLSTATE 40001 instead, so the handler must fold both shapes into one conflict response.
- Keep UNIQUE (resource_id, version) even though the predicate already serialises writers. It is what makes a lost update unwritable if any other path ever reaches the revision table, and it converts a logic bug into 23505 rather than into a silently missing history row.
Follow-up
- A client sends the version it read ten minutes ago and the resource has moved three versions. What is in your 409 so it can resolve the conflict without a full re-fetch?
- Two editors, two disjoint fields, no overlap. Does your answer still refuse the second write, and should it?
Explain the Model-View-Controller (MVC) pattern and how you would implement it in a project.
Explain the Model-View-Controller (MVC) pattern and how you would implement it 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?
How do you ensure the quality of your code? Discuss the testing frameworks you use.
How do you ensure the quality of your code? Discuss the testing frameworks you use.
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 scenario where the application you built is running slow, how would you diagnose the issue?
Given a scenario where the application you built is running slow, how would you diagnose the issue?
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 feature based on user feedback, what steps would you take?
If you were tasked with improving a 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?
Design a system that can handle millions of healthcare records. What considerations would you take into accoun
Design a system that can handle millions of healthcare records. What considerations would you take into account?
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?
How would you ensure data security and compliance in your design?
How would you ensure data security and compliance in your design?
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?
One log partition stops advancing while the others drain
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
- 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.
- 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.
- 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.
- 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?
Built from the rounds and topics Health Catalyst candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Health Catalyst loop
- Write out the reported sequence: Phone Screen, Coding Assessment, On-site/Virtual Interview.
- 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.
02Work SQL
- Spend the session on SQL, which Health Catalyst candidates report being tested on.
- Write one worked example in SQL and time yourself on it.
Deliverable: One timed worked example in SQL.
03Work AngularJS
- Spend the session on AngularJS, which Health Catalyst candidates report being tested on.
- Write one worked example in AngularJS and time yourself on it.
Deliverable: One timed worked example in AngularJS.
04Work Design Patterns
- Spend the session on Design Patterns, which Health Catalyst candidates report being tested on.
- Write one worked example in Design Patterns and time yourself on it.
Deliverable: One timed worked example in Design Patterns.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: Explain the Model-View-Controller (MVC) pattern and how you would implement it in a project.
- Answer aloud, timed: How do you ensure the quality of your code? Discuss the testing frameworks you use.
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 faced a challenge in a project. How did you overcome it?
- 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.
07Answer out loud: Problem-Solving / Case Studies
- Answer aloud, timed: Given a scenario where the application you built is running slow, how would you diagnose the issue?
- Answer aloud, timed: If you were tasked with improving a feature based on user feedback, 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.
Describe a time when you faced a challenge in a project. How did you overcome it?
Describe a time when you faced a 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 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?
What does teamwork mean to you, and how do you foster collaboration?
What does teamwork mean to you, and how do you foster collaboration?
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 when you faced a challenge in a project. How did you overcome it?
- 02
How do you prioritize your tasks when working on multiple projects?
- 03
What does teamwork mean to you, and how do you foster collaboration?
What is the typical interview difficulty and preparation time?
The interview process is generally considered to be of average difficulty, with candidates typically spending a few weeks preparing, especially for the coding assessments and technical interviews.
Health Catalyst Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates often demonstrate a strong alignment with Health Catalyst’s mission, possess the required technical skills, and show effective problem-solving and collaboration abilities.
Health Catalyst Software Engineer candidate reports ↗How would you describe the culture and working style at Health Catalyst?
The culture at Health Catalyst is collaborative and mission-driven, emphasizing innovation and continuous improvement in healthcare technology.
Health Catalyst Software Engineer candidate reports ↗What is the typical timeline from initial screen to offer?
Candidates can expect the process to take several weeks, with timely communication throughout the stages, although feedback on assessments may be delayed.
Health Catalyst Software Engineer candidate reports ↗Are there options for remote work or hybrid arrangements?
Health Catalyst has embraced flexible work arrangements, with remote and hybrid options available depending on the role and team needs.
Health Catalyst Software Engineer candidate reports ↗What topics does Health Catalyst test in interviews?
Health Catalyst interviews most often cover SQL, Stakeholder Management, Behavioral Interviewing, Data Analysis, and Data Visualization. The exact emphasis depends on the specific role you apply for.
Health Catalyst 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.
- 01Health Catalyst 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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