As a Software Engineer at SEP, you are not just writing code; you are a consultant and a technical partner. You will work on a variety of projects that span different industries, requiring you to adapt quickly to new domains, technologies, and team dynamics. Your impact is measured by your ability to solve complex problems, maintain high standards of code quality, and effectively communicate technical solutions to both team members and clients. This role is critical because SEP prides itself on its engineering culture and its commitment to delivering high-quality, reliable software. You will often find yourself in a collaborative, office-based environment where you are expected to be an active participant in team discussions, code reviews, and project planning. The work is challenging and requires a mix of deep technical proficiency, architectural thinking, and a genuine interest in the business outcomes of the software you build.
Online Assessment
reportedCandidates begin with an online technical assessment or a phone screen.
What to demonstrate
- Candidates begin with an online technical assessment or a phone screen
- Depth in Digital electronics (amplifiers/transistors)
How to prepare
- Answer aloud and timed: How would you debug a faulty code ticket in a production environment?
- Answer aloud and timed: Can you explain how changing specific transistor characteristics impacts amplifier design?
Onsite Interview
reportedAn intensive in-person or virtual day focusing on technical skills and problem-solving.
What to demonstrate
- An intensive in-person or virtual day focusing on technical skills and problem-solving
- Depth in Digital electronics (amplifiers/transistors)
How to prepare
- Answer aloud and timed: Walk us through a time you had to optimize a piece of code that was not performing at scale.
- Answer aloud and timed: How do you approach a technical problem that you have never encountered before?
Team Interactions
reportedCandidates meet multiple team members and engage in collaborative discussions.
What to demonstrate
- Candidates meet multiple team members and engage in collaborative discussions
- Depth in Digital electronics (amplifiers/transistors)
How to prepare
- Answer aloud and timed: Explain the architecture of a project you are particularly proud of.
- Answer aloud and timed: How do you balance the need for rapid development with long-term code maintainability?
Whiteboard Problems
reportedSignificant time is spent on whiteboard problems to assess technical abilities.
What to demonstrate
- Significant time is spent on whiteboard problems to assess technical abilities
- Depth in Digital electronics (amplifiers/transistors)
How to prepare
- Answer aloud and timed: What are the common trade-offs you consider when choosing a technology stack for a new project?
- Answer aloud and timed: Tell us about a time you had to explain a complex technical concept to a non-technical stakeholder.
PracHub editorial advice for the preparation topics above.
Lead the interview
Do not wait for the interviewer to guide every moment. If there is a pause, ask a question about their current projects or the team's engineering process.
Bring your own questions
Have a list of thoughtful, prepared questions ready for every person you meet. This demonstrates your genuine interest in SEP.
Be ready to show your work
Whether it is code on a laptop or a diagram on a whiteboard, be prepared to demonstrate your technical history and the projects you have led.
Stay engaged
Even if the interview day feels long, maintain your energy. Your level of engagement is a signal of your potential as a team member.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Can you explain how changing specific transistor characteristics impacts amplifier design?
Can you explain how changing specific transistor characteristics impacts amplifier design?
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?
Walk us through a time you had to optimize a piece of code that was not performing at scale.
Walk us through a time you had to optimize a piece of code that was not performing at scale.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
How do you approach a technical problem that you have never encountered before?
How do you approach a technical problem that you have never encountered before?
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 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?
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 the architecture of a project you are particularly proud of.
Explain the architecture of a project you are particularly proud of.
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 do you balance the need for rapid development with long-term code maintainability?
How do you balance the need for rapid development with long-term code maintainability?
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 are the common trade-offs you consider when choosing a technology stack for a new project?
What are the common trade-offs you consider when choosing a technology stack for a new 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?
Tell us about a time you had to explain a complex technical concept to a non-technical stakeholder.
Tell us about a time you had to explain a complex technical concept to a non-technical stakeholder.
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 working with a team under strict project constraints.
Describe your process for working with a team under strict project constraints.
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 debug a faulty code ticket in a production environment?
How would you debug a faulty code ticket 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 SEP candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the SEP loop
- Write out the reported sequence: Online Assessment, Onsite Interview, Team Interactions, Whiteboard Problems.
- 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 Digital electronics (amplifiers/transistors)
- Spend the session on Digital electronics (amplifiers/transistors), which SEP candidates report being tested on.
- Write one worked example in Digital electronics (amplifiers/transistors) and time yourself on it.
Deliverable: One timed worked example in Digital electronics (amplifiers/transistors).
03Work Whiteboard problem solving
- Spend the session on Whiteboard problem solving, which SEP candidates report being tested on.
- Write one worked example in Whiteboard problem solving and time yourself on it.
Deliverable: One timed worked example in Whiteboard problem solving.
04Work Circuit/analog design reasoning
- Spend the session on Circuit/analog design reasoning, which SEP candidates report being tested on.
- Write one worked example in Circuit/analog design reasoning and time yourself on it.
Deliverable: One timed worked example in Circuit/analog design reasoning.
05Answer out loud: Technical Proficiency and Problem Solving
- Answer aloud, timed: How would you debug a faulty code ticket in a production environment?
- Answer aloud, timed: Can you explain how changing specific transistor characteristics impacts amplifier design?
Deliverable: Spoken answers to 2 reported Technical Proficiency and Problem Solving question(s), under time.
06Answer out loud: Architectural Thinking
- Answer aloud, timed: Explain the architecture of a project you are particularly proud of.
- Answer aloud, timed: How do you balance the need for rapid development with long-term code maintainability?
Deliverable: Spoken answers to 2 reported Architectural Thinking question(s), under time.
07Answer out loud: Communication and Collaboration
- Answer aloud, timed: Tell us about a time you had to explain a complex technical concept to a non-technical stakeholder.
- Answer aloud, timed: How do you handle disagreements within your team regarding technical direction?
Deliverable: Spoken answers to 2 reported Communication and Collaboration 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.
How do you handle disagreements within your team regarding technical direction?
How do you handle disagreements within your team regarding technical direction?
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?
Argue against a design, lose, and commit anyway
Describe a design you argued against and lost. State the failure you predicted as a named mechanism, not a feeling about complexity: two services that would need one transaction, a projection with no rebuild path, a write path with no idempotency key. Say what evidence you brought, what the decision maker weighed instead, and what you did after the decision was made: what you instrumented, what you wrote down, and whether the prediction came true. Five minutes.
Approach
- State the prediction in falsifiable form up front: the mechanism, the condition that triggers it, and the observable outcome. A prediction that cannot be checked also cannot be credited to you later.
- Show the evidence you had at the time and label each piece honestly as measured, analogous, or intuition. Keeping the intuition is fine; disguising it as data is the thing that erodes your standing in the next argument.
- Represent the opposing case at full strength, including the constraint you did not control: a fixed date, a team boundary, or the fact that the decision was cheap to reverse and yours was not.
- Make disagree-and-commit concrete. Name the artefact you left behind so the prediction could be settled without you: the alert and its threshold, the counter on the dashboard, the decision note that recorded the trade-off and the condition that would revisit it.
Follow-up
- What threshold on that alert would have proved you right, and did anyone ever look at it?
- If the same proposal arrived tomorrow with the same deadline, would you argue it the same way?
Unblock an engineer without taking the keyboard
A teammate has spent two days on a job handler that occasionally writes duplicate rows. They are certain the queue is delivering twice by mistake. You suspect a lease expiring under a slow handler, so the job is running concurrently with itself. Describe how you have unblocked someone in this position: what you asked before offering a hypothesis, what you showed them rather than told them, and what you left them owning. Then say what you would do if their theory turned out to be the right one.
Approach
- Ask before diagnosing, and ask for things answerable from data they already have: the attempt count on the job rows that produced duplicates, the handler's observed duration against its lease expiry, and whether the duplicate rows share a natural key that a unique constraint could have caught.
- Teach the shape rather than the answer. A lease cannot distinguish a dead worker from a slow one, so a handler that outruns its lease is running twice by design, and deploys deliver the other half by killing handlers mid-run on every rollout. Both of their candidate theories produce identical duplicate rows, which is why the evidence has to come from timings rather than from argument.
- Hand over a checklist they execute: a natural key on every write the handler performs so the second copy collides rather than appends, the record of intent written before any external effect, a lease heartbeat while running, and the metric that shows it working.
- Keep ownership with them deliberately. Pair on the first write, then step back; if you finish it yourself you have closed one ticket and left the same person stuck on the next redelivery.
Follow-up
- How would you distinguish a genuine double-delivery from a lease expiry using only the data already stored?
- Their handler calls an external endpoint before recording that it did. What do you tell them to change first?
- 01
How do you handle disagreements within your team regarding technical direction?
- 02
Describe a design you argued against and lost. State the failure you predicted as a named mechanism, not a feeling about complexity: two services that would need one transaction, a projection with no rebuild path, a write path with no idempotency key. Say what evidence you brought, what the decision maker weighed instead, and what you did after the decision was made: what you instrumented, what you wrote down, and whether the prediction came true. Five minutes.
- 03
A teammate has spent two days on a job handler that occasionally writes duplicate rows. They are certain the queue is delivering twice by mistake. You suspect a lease expiring under a slow handler, so the job is running concurrently with itself. Describe how you have unblocked someone in this position: what you asked before offering a hypothesis, what you showed them rather than told them, and what you left them owning. Then say what you would do if their theory turned out to be the right one.
How difficult are the technical problems?
The problems range from straightforward to challenging. They are designed to test your problem-solving ability rather than your memory of specific algorithms. Focus on communicating your thought process clearly.
SEP Software Engineer candidate reports ↗What if I don't know the answer to a technical question?
Be honest. It is perfectly acceptable to explain how you would go about finding the answer or what your initial hypothesis is. We value candidates who can work through a problem logically, even when they don't have the immediate solution.
SEP Software Engineer candidate reports ↗How should I prepare for the "teach us something" portion of the interview?
Choose a topic you are genuinely passionate about and know deeply. Practice explaining it to a friend who is not an expert; if they can follow your logic, you are on the right track.
SEP Software Engineer candidate reports ↗What is the company culture like?
SEP values a professional, collaborative environment. We look for engineers who are not only technically proficient but also good teammates who contribute positively to the office environment. Some candidates have reported feeling that interviewers were disengaged. Do not let this affect your performance. Stay focused, lead the conversation, and continue to ask high-quality questions regardless of the interviewer's demeanor.
SEP Software Engineer candidate reports ↗What topics does SEP test in interviews?
SEP interviews most often cover Digital electronics (amplifiers/transistors), Whiteboard problem solving, Circuit/analog design reasoning, Debugging, and Data Structures & Algorithms (DSA). The exact emphasis depends on the specific role you apply for.
SEP 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.
- 01SEP 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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