UCLA Health · Software Engineer
Updated · 2026-09-24

UCLA Health Software Engineer
Interview Questions & Guide 2026

THE 60-SECOND BRIEF

As a Software Engineer at UCLA Health, you are at the intersection of cutting-edge technology and mission-critical patient care. Your work is not just about writing code; it is about building and maintaining the digital infrastructure that supports world-class medical research, clinical operations, and health outcomes. Whether you are working on internal department tools, cloud-based infrastructure, or data-driven applications, your contributions directly impact how healthcare professionals access information and deliver services.

Most rounds test how you handle an under-specified problem more than what you recall. A wrong first approach you correct out loud is recoverable; a constraint you assumed silently and were never given is the expensive mistake.

UCLA Health candidates report 3 rounds · ≈ 3-5 weeks. The stages below are what candidates describe, not a published process.

Version clinical results instead of updating rows in placeDesign person merges that remain reversible afterwardsMake HL7 and X12 ingestion idempotent under replay

34 min read

Practice 13 Software Engineer prompts
13Practice promptsAcross five skill areas
3With worked solutionsIncluded in the practice prompts

As a Software Engineer at UCLA Health, you are at the intersection of cutting-edge technology and mission-critical patient care. Your work is not just about writing code; it is about building and maintaining the digital infrastructure that supports world-class medical research, clinical operations, and health outcomes. Whether you are working on internal department tools, cloud-based infrastructure, or data-driven applications, your contributions directly impact how healthcare professionals access information and deliver services.

This role requires a unique blend of technical precision and adaptability. Because UCLA Health is a large-scale academic medical environment, you will often find yourself navigating complex systems where reliability and security are paramount. Candidates who thrive here are those who can balance the need for rigorous, stable engineering with the creative problem-solving required to modernize legacy systems or implement new cloud-based solutions. If you are passionate about applying your software skills to a high-stakes, mission-driven environment, this position offers significant professional impact.

01

HR/Managerial Screen

reported

You cannot drill a format you do not know, so put the preparation into material that travels. Three pieces of your own work, each rehearsed until you can take a follow-up you did not anticipate, will carry a conversation or a code walkthrough equally well. Specificity is what separates that from filler. A number needs its definition before it means anything: a p99 is over some window and measured at some hop, and a server-side figure excludes the queueing and network time a client would see. The number you cannot qualify is the one to leave out.

What to demonstrate

  • Whether your examples carry detail only someone who did the work would hold, such as what the binding constraint actually was, which alternative you rejected and why it was worse, and what you measured on each side of the change
  • Whether a number survives one follow-up, meaning you can say what it was measured over and whether it moved because of your change or merely alongside it
  • Whether a failure is described with the specific change that followed it, rather than a lesson stated in general terms
  • Whether your part in a team effort is stated accurately, including what other people did

How to prepare

  • Write a page on each of three projects covering the constraint, the option you rejected, the measurement before and after, and what went wrong. Cut any line you cannot take a follow-up on, since you are writing the parts you will be pressed on rather than a summary.
  • Recover the real figures while you still have access: request volume, data size, latency with its percentile and window, team size, timeline. Note where each came from, whether a dashboard, a design document or memory, and mark the estimates so you can say which they are out loud.
  • Take your weakest project story to someone who works in a different area and have them ask why four times in succession. The point where you run out of answer is the part to go and re-read before the round.
PracHub interview research ↗
02

Technical Assessment

reported

The same problem is scored by two different mechanisms depending on the format, and preparing for one does not cover the other. With a person watching, partial progress is visible and a hint is a correction you can absorb; silence is the expensive failure, because nobody can read a half-written function. With an automated grader there is no partial credit for what you were about to do, nobody to ask, and the worked examples in the prompt are the entire specification. Read them as a contract, down to whether an empty result should be an empty list or no output at all.

What to demonstrate

  • In a live session, whether your commentary tracks what your hands are doing, and whether a hint redirects you or gets defended against
  • In an automated one, whether you cover the cases the examples do not show, since the hidden cases are where the score moves
  • Whether you manage the clock on purpose: abandoning an approach that is not converging while there is still time to write something simpler that finishes

How to prepare

  • Have someone hand you a problem and feed you one deliberately wrong hint. Practise testing it against a concrete case instead of accepting or rejecting it on authority.
  • Do one timed run a week in a plain browser editor with autocomplete, linting and your own snippets switched off, which is closer to what these environments give you
  • For the automated format, write the harness before the solution: a main that feeds the worked examples plus an empty and a single-element case and prints expected against actual, so a wrong submission is caught by you first
PracHub interview research ↗
03

In-Person/Virtual Panel Interview

reported

Coding rounds mostly set a floor. They decide whether you clear the bar, not where you land on the ladder. Level tends to come out of the design discussion and the ownership stories, so the question worth auditing beforehand is whether the scope you describe matches the scope of the job. Work that stops at your own service, or a story whose hard part was writing the code rather than getting several people to agree on an interface, reads a level below where you think you are interviewing, and that gap is usually resolved downwards.

What to demonstrate

  • Whether the largest thing you describe owning ran end to end — the decision, the migration path, the rollout, and what you did when it went wrong — or stopped at the change you merged
  • Whether design answers include what you would not build, what you would defer, and what you would measure before committing, rather than only what the boxes are
  • Whether a disagreement in a story was settled with something checkable — a benchmark, a prototype, a written proposal — instead of by seniority or by waiting it out
  • Whether you can say which calls you made alone and which you escalated, and why the line sat where it did

How to prepare

  • Write your largest piece of owned work as a timeline of decisions — who decided what, when, and what you did when the plan broke — then delete every sentence whose subject is "we" and see how much survives
  • Take one system you know well and drill the migration answer: how old and new paths run side by side under live traffic, how you compare their outputs, what the rollback is once writes are going to both, and which step you would not automate
  • Map each line of the ladder in the job posting to a specific thing you have done, find the line you cannot support, and prepare the closest evidence you have plus an honest account of the gap
PracHub interview research ↗

PracHub editorial advice for the preparation topics above.

01

Writing the access audit record inside the read transaction, or firing it off after the response with no durability.

Inside the transaction, an audit-store outage blocks clinical reads and turns a logging dependency into a care outage. Fire-and-forget afterwards means the audit trail is incomplete during precisely the incidents it exists to reconstruct, and the gaps are invisible until someone asks for the log. The usual resolution is committing the access decision and its audit row together to a local outbox and shipping asynchronously, which keeps the read path available while preserving durability.

02

Treating a medical record number or a member ID as a globally unique key and joining on it directly.

These identifiers are unique only within the authority that issued them. Two facilities in one network routinely have the same medical record number for different people, and member IDs get reissued when someone changes plans. Joining on the bare value merges two patients' records, which is the most damaging failure available in this domain, and it passes every test written against a single-facility fixture because the collision only appears once a second source is connected.

03

Never running a concrete value through the code

Trace one small input and one edge input by hand, index by index, out loud. Re-reading your own code catches design mistakes; walking a real value through it catches the off-by-one, the uninitialised accumulator and the loop that never advances.

04

Optimising an axis nobody named

Ask which resource is actually scarce here: wall-clock latency, throughput, memory footprint, cost per request, or engineering time. Shaving a constant factor off an in-memory step is wasted effort when the same function makes a blocking remote call inside the loop.

Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.

9 technical prompts3 include a worked solution

Flag a requester reading too many distinct charts per window

mediumWorked solution
sliding windowtwo pointersdistinct count

You consume access-audit records (event_ts, requester_id, enterprise_person_id, purpose_of_use, break_glass) at tens of thousands per second, non-decreasing in event_ts. For each requester, emit an alert the first time any sliding 600-second window contains reads of more than D distinct enterprise_person_ids. Break-glass reads count toward the window and are also reported separately. Return (requester_id, window_start_ts, distinct_count). Target O(1) amortised per event and memory proportional to the events resident in the window, not to the day.

Approach
  1. Per requester, hold a deque of (event_ts, person_id) and a hash map from person_id to its occurrence count inside the window, plus a running distinct counter. Push on the right; while the front is older than event_ts minus 600 seconds, pop it, decrement its count and erase the key when the count reaches zero, decrementing the distinct counter. Each event is pushed once and popped once, so the amortised cost is O(1) and the memory is O(W) for window occupancy W.
  2. Test the threshold immediately after each push and nowhere else. Between two consecutive events the window can only lose members as its left edge advances, so the maximum distinct count over all window positions is attained at a position whose right edge is an event. Checking at pushes is therefore exhaustive rather than a sampling approximation.
  3. Latch the alert per requester and re-arm only when the distinct count falls back below D, otherwise one busy stretch emits thousands of near-identical rows and the real signal is buried by its own volume.
  4. Bound memory both per requester and globally. A requester whose window legitimately holds tens of thousands of reads must not hold the process hostage, so cap the deque and degrade above the cap to an approximate distinct counter such as HyperLogLog, stating the error you accept in exchange.
  5. Count break-glass toward the window but carry it in its own output field. Break-glass has to succeed during an emergency, which is exactly why it must be the most visible path in the audit, and excluding it from the count would make the abuse route the quiet one.
  6. State the precondition: this is correct only while input is non-decreasing in event_ts. Out-of-order arrival needs a bounded-lateness buffer and a watermark, and dropping late events without a counter is the failure that hides itself.
Worked solution 25 min
  1. Implement push, then the eviction loop, then the distinct counter update, in that order, and assert the counter against the map size after each event.
  2. Set D to 25 and feed 15 distinct persons between 09:06:00 and 09:08:59.
  3. Feed 15 more distinct persons from 09:11:00, one every eight seconds.
  4. Record the event at which the alert fires and the window_start it reports.
  5. Re-run the same events through fixed ten-minute tumbling buckets and compare.
EXPECTED RESULTThe 26th distinct read lands at 09:12:20, its window covers 09:02:20 to 09:12:20 and holds all 15 from the first group plus 11 from the second, so the alert is (requester, 09:02:20, 26). Tumbling buckets of 09:00 to 09:10 and 09:10 to 09:20 see 15 and 15, and never fire.
Follow-up
  • One region's events arrive up to 90 seconds late. What buffer do you add, and what does that do to alert latency?
  • One person uses two requester accounts. What has to change in the key, and what new false positive does that introduce?
  • How do you restore window state after a process restart without replaying the whole day?

Resolve enterprise identity from a link log that supports unmerge

hard
union-findrollbackidentity resolution

person_identity_link holds link_id, enterprise_person_id, assigning_authority, source_person_id, match_score, link_status (auto_linked, manual_linked, potential_duplicate, unlinked, rejected), version, superseded_by_link_id, decided_by, decided_at. You have up to 40 million source identities and 60 million decisions applied in decided_at order. Build a structure answering which enterprise identity a given (assigning_authority, source_person_id) resolves to after any prefix of the log, and supporting a revert of the k most recent merges at O(1) each. State the query complexity, and say why path compression is unavailable to you.

Approach
  1. Intern the node key as the pair (assigning_authority, source_person_id) into a dense integer index. Never key on source_person_id alone: two facilities in one network routinely issue the same medical record number to different people, so a bare-value key merges two patients before any matching logic has run, and a single-source test fixture will never show it.
  2. Classify the log rows before touching the structure. auto_linked and manual_linked are unions; potential_duplicate and rejected are recorded decisions that must not union anything; unlinked is a revert of the link it supersedes, not a new edge.
  3. Use union by size with an explicit undo stack, pushing (attached_root, its previous parent, the previous size of the absorbing root) on every union. Find walks parent pointers to the root: union by size bounds tree height at log2(n), so a query is O(log n) worst case, a union is O(log n), and a revert pops two words and is O(1).
  4. Path compression is the thing you have to give up, and the reason is specific: it rewrites parent pointers of nodes that were never named in the union being recorded, so the undo entry no longer describes the mutation that happened and a revert restores a forest that is quietly wrong. Near-constant find is only available to an append-only structure.
  5. Hold enterprise_person_id as a property of the root slot rather than a value copied onto every member. A merge then relabels one slot instead of n rows, and an unmerge restores two labels instead of reconstructing n.
  6. State the price plainly: every read path gains a resolution hop and no downstream table can carry a plain patient_id column. That cost is what buys reversibility, and it belongs in the design discussion rather than being discovered later by whoever writes the first join.
Follow-up
  • A merge is found wrong three weeks and 200,000 unions later, and your stack only reverts a suffix. What do you do instead, and what does that cost?
  • A claim was posted under the losing identity before the merge. After the unmerge, which identity owns it, and what in your design let you answer that?
  • Two matcher instances submit unions concurrently. What is the smallest change that keeps both the structure and the undo stack consistent?

Flatten overlapping coverage spans into a primary-payer timeline

medium
sweep lineintervalsbitemporal

For one enterprise_person_id you hold up to 10,000 coverage_span rows: coverage_id, payer_id, plan_id, effective_date, termination_date (null means open-ended), coverage_order (1 is primary), status, valid_from and valid_to (system time). Given a system instant T and a date range D0 to D1, return disjoint business-date intervals covering that range, each labelled with the active coverage_id of lowest coverage_order, and with uncovered stretches returned explicitly. termination_date is the last covered day. Only status active counts. Target O(N log N) time, O(N) space.

Approach
  1. Apply the system-time slice before any interval logic: keep rows where valid_from is at or before T and valid_to is after T. That single predicate is what makes the answer 'what we believed at T' rather than 'what we believe now', and a retroactive termination loaded after T leaks straight into the output if you skip it.
  2. Convert each surviving row to a half-open day interval from effective_date up to termination_date plus one day, using positive infinity for a null termination. Half-open removes every off-by-one at the join between a termination and the next plan's effective date, which is where same-day switches get turned into false gaps.
  3. Sweep: emit 2N boundary events, sort by date in O(N log N), and hold the active set in a min-heap keyed by (coverage_order, coverage_id) with lazy deletion, popping the top while it has already expired at the current boundary. Each coverage is pushed once and popped once, so the sweep is O(N log N) total and O(N) space.
  4. Emit an output interval whenever the heap top changes between consecutive boundaries, and emit an explicit uncovered interval when the heap empties. A gap reported as a gap is a different answer from a gap omitted, and downstream the difference is a denial versus a silent assumption of coverage.
  5. Fix the tie-break and state it: lowest coverage_order, then lowest coverage_id. Two rows at order 1 is a data error, and without a deterministic rule the coordination-of-benefits answer changes between two runs over identical data.
  6. Clip to D0 and D1 last, so a coverage that starts before D0 still contributes its correct order inside the window.
Follow-up
  • Run the same query at two system instants and diff the timelines. What did the correction change, and what does each extra instant cost you?
  • A termination arrives with an effective date earlier than the service date of a claim that already adjudicated and paid. What does the timeline now say, and what has to happen to that claim?
  • Two enrolment files disagree on coverage_order for a dependent. What does your tie-break do, and what should the system do instead of tie-breaking?

Four days sample coding, design, fundamentals and the practical rounds at deliberately shallow depth, which is enough to surface the topics you did not know were in scope. That map, rather than a guess made on day one, decides where the last three days go.

Small steps. Visible outcomes.0 / 7 completed
ONE WEEK · YOUR PACE

Prepare, practise & reflect

One practical outcome each day. Spend longer where you need it.

0 / 7 done
01Coding, one pass at shallow depth
  • Solve one problem from each of six families, an array with two pointers, hash counting, binary search, a tree traversal, a graph traversal and one dynamic program, under a hard twenty-minute cap with no extensions, marking each finished, late, or stalled.
  • For every stall, write the exact move you could not make rather than the subject, so the note reads could not turn the recurrence into a loop rather than bad at dynamic programming.
  • Fix nothing today. The value of the pass is the unfixed record.

Deliverable: Six timed attempts marked finished, late or stalled, each stall carrying a named blocking move.

Practice prompt ↗Practice prompt ↗Worked solution ↗
02Design, one pass at shallow depth
  • Spend twenty minutes each on three different shapes, a read-heavy feed, a write-heavy ingest path, and something needing a transaction across two entities, stopping each at requirements, interface and data model.
  • After each, write the first question you could not answer, which is usually a number you could not estimate or a failure mode you had no vocabulary for.
  • Mark which of the three you would be most relieved not to be asked, and treat that as data rather than as a preference.

Deliverable: Three shallow designs, each with the first unanswerable question written at the bottom.

Practice prompt ↗Practice prompt ↗
03Fundamentals and the practical rounds
  • Answer eight short questions in writing at four minutes each, covering the material that fills the gaps between the big rounds: what happens between a URL and a rendered page, what an index costs on write, when a process is preferable to a thread, and what conditions a deadlock requires.
  • Do one thirty-minute practical task of the kind a take-home compresses: read an unfamiliar two-hundred-line file and write what it does, what you would change, and the one thing you remain unsure of.
  • Score every answer fluent, correct but slow, or absent, and keep the absent ones visible.

Deliverable: Eight scored short answers and one written reading of unfamiliar code.

Practice prompt ↗Practice prompt ↗
04The rounds that are about you, and the map
  • Deliver three behavioural answers aloud against a timer, a conflict, a failure you owned, and a decision made without enough information, marking any that ran past three minutes or contained no number.
  • Assemble the map: every marked item from days one to three on a single page, sorted by how likely it is to appear in your loop rather than by how uncomfortable it felt.
  • Choose exactly two areas for the remaining three days and write down what you are deliberately abandoning.

Deliverable: A one-page scored map of the whole surface area with two areas chosen and the rest explicitly abandoned.

Practice prompt ↗Practice prompt ↗Worked solution ↗
05First chosen area, to the depth you skipped
  • Work the higher-ranked area in four focused blocks, choosing items one level above where you stalled rather than repeating what already works.
  • After each block write the rule you extracted in one sentence with its precondition attached, since a rule carrying no precondition is exactly what fails under a variation.
  • Re-attempt the day-one or day-two item that exposed this area and compare against the original timing.

Deliverable: Four worked blocks, a timed re-attempt against the original, and three one-sentence rules with preconditions.

Practice prompt ↗Practice prompt ↗
06Second chosen area, where the gap is coverage rather than speed
  • Treat the second area differently from the first. Day five drilled something you could already half-do; this one is usually a topic you had simply never met, so build one worked reference example end to end and keep it, rather than attempting six problems badly.
  • Write down the vocabulary you were missing on day two or three, five terms at most, each with the one sentence that makes it usable in an answer rather than the textbook definition.
  • Redo the shallow attempt that exposed this area and note whether you now fail later in the problem, because moving the failure point is the realistic gain from a single day and is worth more than a score that did not change.

Deliverable: One worked reference example for the newly covered area, a five-term vocabulary list, and a note on where the failure point moved.

Practice prompt ↗Practice prompt ↗
07Reassemble the loop
  • Sit two rounds back to back with no gap, ordering them so the area you chose second comes last, because the map was built from rested, isolated attempts and the loop will reach your weaker area when you are already spent.
  • Write where the second round suffered from the first, which is normally the point at which structure collapses into narration.
  • Reduce the week to one page holding only the rules you can state without reading them.

Deliverable: Mock notes on cross-round carryover plus a one-page card of rules you can recite from memory.

Practice prompt ↗Worked solution ↗

Expand any day for tasks and deliverables. Your progress is saved on this device.

Every story you tell gets read for blast radius and judgement: what could have broken, who else it touched, what you knew at the moment you decided. Nobody can audit your code in an hour, so they audit your reasoning instead. Pick work where the call was genuinely yours and the consequences were real enough to remember.

Tell me about your interest in this specific position at UCLA Health.

medium
behavioural and engineering judgement

Tell me about your interest in this specific position at UCLA Health.

Approach
  1. Give the blast radius: what could have broken, and what you measured.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Name the disagreement and how you resolved it with evidence.
Follow-up
  • What would you do differently if you ran that again?
  • What did you decide not to do, and why?

Tell me about a time you were working in a team setting and encountere…

medium
behavioural and engineering judgement

Tell me about a time you were working in a team setting and encountered an issue you had to resolve together.

Approach
  1. Give the blast radius: what could have broken, and what you measured.
  2. Pick a story where you made the decision, not one where you watched it.
  3. Name the disagreement and how you resolved it with evidence.
Follow-up
  • What would you do differently if you ran that again?
  • What did you decide not to do, and why?

Tell me more about your responsibilities and contributions in your las…

medium
behavioural and engineering judgement

Tell me more about your responsibilities and contributions in your last role.

Approach
  1. Give the blast radius: what could have broken, and what you measured.
  2. Close with what you would do differently, concretely.
  3. State the situation in two sentences and spend the rest on the reasoning.
Follow-up
  • How did you know your change caused the improvement?
  • What did you decide not to do, and why?

How do you fit in with this position and the broader team culture?

medium
behavioural and engineering judgement

How do you fit in with this position and the broader team culture?

Approach
  1. Close with what you would do differently, concretely.
  2. Give the blast radius: what could have broken, and what you measured.
  3. Name the disagreement and how you resolved it with evidence.
Follow-up
  • What did you decide not to do, and why?
  • How did you know your change caused the improvement?
  • 01

    Tell me about your interest in this specific position at UCLA Health.

  • 02

    Tell me about a time you were working in a team setting and encountered an issue you had to resolve together.

  • 03

    Tell me more about your responsibilities and contributions in your last role.

  • 04

    How do you fit in with this position and the broader team culture?

PracHub interview preparation framework ↗
Is this an official UCLA Health interview guide?

No. It is PracHub's own research and practice material for the Software Engineer role at UCLA Health. Rounds and questions reflect what candidates have reported, not a process UCLA Health has published, and they change over time. Confirm the current format and scope with your recruiter.

PracHub interview research ↗
How long does the interview process typically take?

The process can vary, but candidates often report a timeline of several weeks from the initial screening to a final decision. Be prepared for a process that involves multiple rounds of interviews with different team members.

PracHub interview research ↗
What differentiates successful candidates?

Successful candidates are those who can clearly articulate their past projects and technical choices. The ability to explain "why" you built something a certain way is often as important as the code itself.

PracHub interview research ↗
Is there a specific focus on medical knowledge?

While you do not need to be a clinician, having an understanding of healthcare data or the unique challenges of a hospital environment is a significant advantage.

PracHub interview research ↗
Sources & methodology 3 sources ↗

Official role evidence, timestamped platform data and clearly labeled preparation advice.