As a Software Engineer at LevelUp, you are at the center of a platform designed to bridge the gap between businesses and their customers through seamless digital integration. You will contribute to a high-scale environment where your code directly impacts the reliability and functionality of payment processing, loyalty programs, and merchant-facing tools. This role requires a balance of technical precision and product-minded thinking, as you will often work on problems that require both clean architecture and an intuitive understanding of the user experience. Success in this position means more than just writing functional code; it requires a commitment to maintainable, test-driven development. Because LevelUp often operates within complex, distributed systems, you will be expected to demonstrate an ability to navigate existing codebases, troubleshoot production issues, and collaborate closely with cross-functional teams. You will have the opportunity to solve challenges that directly influence how merchants connect with consumers, making your contributions highly visible and essential to the company’s core business operations.
Recruiter Screen
reportedInitial discussion with a recruiter to cover logistics and your background.
What to demonstrate
- Initial discussion with a recruiter to cover logistics and your background
- Depth in Algorithmic Problem Solving
How to prepare
- Be able to walk your CV end to end in two minutes, and say why this company specifically.
- Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.
Technical Assessments
reportedA series of assessments including take-home coding challenges and virtual coding sessions.
What to demonstrate
- A series of assessments including take-home coding challenges and virtual coding sessions
- Depth in Algorithmic Problem Solving
How to prepare
- Answer aloud and timed: Write a function that checks if all alphabet letters are present in a phrase.
- Answer aloud and timed: Implement a mechanism for counting instantiated classes.
Onsite Visit
reportedMultiple back-to-back interviews with members of the engineering team.
What to demonstrate
- Multiple back-to-back interviews with members of the engineering team
- Depth in Algorithmic Problem Solving
How to prepare
- Answer aloud and timed: Read through existing production code and explain the design.
- Answer aloud and timed: Write a RESTful app that can accept and parse log data.
PracHub editorial advice for the preparation topics above.
Show your work
When solving problems, explain your trade-offs. Why did you choose one data structure over another?
Be proactive
If the interviewer is quiet, keep them updated on your progress. It demonstrates confidence and collaboration.
Research the product
Spend time understanding how LevelUp functions from a user's perspective. It will make your behavioral answers much more grounded.
Clarify requirements
Never start coding until you are sure you understand the problem. Asking clarifying questions is a sign of a senior-level engineer.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Write a function to determine if a string is a palindrome.
Write a function to determine if a string is a palindrome.
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?
Find the largest palindrome from the product of two 3-digit numbers.
Find the largest palindrome from the product of two 3-digit numbers.
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 that checks if all alphabet letters are present in a phrase.
Write a function that checks if all alphabet letters are present in a phrase.
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?
Implement a mechanism for counting instantiated classes.
Implement a mechanism for counting instantiated classes.
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?
Keep soft-deleted accounts from blocking re-registration
app_user holds user_id, tenant_id, email CITEXT, password_hash (NULL for SSO principals), email_verified_at, auth_version, status ('invited','active','suspended','deactivated'), created_at, updated_at, deleted_at. Two live accounts for one address inside a tenant must be impossible, but an address freed by a soft delete must be reusable, and the same tenant may delete and re-register it repeatedly. Write the uniqueness DDL for PostgreSQL 16, then the equivalent for MySQL 8 where partial indexes do not exist, and say what each permits once three deleted rows already hold that address.
Approach
- Start from what is actually unique: not (tenant_id, email), but (tenant_id, email) among live rows. PostgreSQL says that directly — CREATE UNIQUE INDEX app_user_live_email ON app_user (tenant_id, email) WHERE deleted_at IS NULL. A full constraint over the same two columns burns the address permanently the first time someone deletes an account.
- Keep case-insensitivity in the type or the index, never in the application: CITEXT as given, or UNIQUE (tenant_id, lower(email)) as an expression index where the extension is unavailable. A case-sensitive unique column is exactly how two accounts for one human appear.
- For MySQL 8 the predicate has to move inside the key: add a discriminator column that is a constant 0 while the row is live and is set to user_id on delete, with UNIQUE (tenant_id, email, deleted_marker). Live rows share the constant and still collide; deleted rows differ from each other and stop colliding.
- State the NULL variant and its dependency: leaving the marker NULL for deleted rows also works, because a unique index treats NULLs as distinct — true in MySQL, and true in PostgreSQL only under the default NULLS DISTINCT, which PostgreSQL 15 lets you reverse. Check the polarity against the three existing deleted rows: constant-on-live is what preserves the collision you want, and reversing it silently admits duplicate live accounts.
Follow-up
- A deleted account re-registers with the same address the next day. Do the old resource rows follow the new user_id, and how does the API keep the two principals apart?
- How do you honour an erasure request while resource_revision.actor_user_id still references this table?
Find version gaps and relay lag with window functions
outbox_event holds event_id, aggregate_type, aggregate_id, aggregate_version, event_type, payload, status ('pending','published','dead'), attempts, created_at, published_at. A projection is missing rows and you must decide whether the relay skipped events or the consumer dropped them. Write three queries over the last seven days: one listing every aggregate_id whose published aggregate_version sequence has a hole, one giving per-day counts with a running total, and one returning the newest published event per aggregate. For each, say where the window function is evaluated relative to WHERE and LIMIT. PostgreSQL 16.
Approach
- Gaps: compute lead(aggregate_version) OVER (PARTITION BY aggregate_id ORDER BY aggregate_version) in a subquery, then filter next_version <> aggregate_version + 1 in the outer query. Window functions are evaluated after WHERE, GROUP BY and HAVING and before the outer ORDER BY and LIMIT, so the predicate cannot sit in the same WHERE clause and PostgreSQL 16 has no QUALIFY.
- Say what the seven-day filter does to the answer: it truncates every partition, so the first row per aggregate has no predecessor inside the window and a hole spanning the boundary is invisible. Widen the window, or join to resource.version as the authority for the true maximum.
- Running total: SELECT date_trunc('day', created_at) AS d, count() AS n, sum(count()) OVER (ORDER BY date_trunc('day', created_at) ROWS UNBOUNDED PRECEDING). An aggregate inside a window call is legal because grouping runs before windowing. The grouping key is unique per row here so ROWS and RANGE agree, but write the frame anyway — over ungrouped rows with tied timestamps the default RANGE frame pulls in every peer row and the total jumps.
- Newest per aggregate: DISTINCT ON (aggregate_id) ... ORDER BY aggregate_id, aggregate_version DESC is the cheap PostgreSQL-only form when an index matches that order; row_number() OVER (PARTITION BY aggregate_id ORDER BY aggregate_version DESC) = 1 is the portable form and needs a subquery for the same evaluation-order reason as the gap query.
Follow-up
- Relay failover redelivers events. Does a duplicate break the gap query, and how would you detect one from this table alone?
- Turn the gap check into a continuous monitor rather than a query someone runs after an incident. What does it watch?
Read through existing production code and explain the design.
Read through existing production code and explain the 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?
Write a RESTful app that can accept and parse log data.
Write a RESTful app that can accept and parse log data.
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?
Design a system or endpoint based on given technical requirements.
Design a system or endpoint based on given technical requirements.
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?
Exports duplicate a row range about once a week
Roughly once a week an export writes a file containing a duplicated range of rows. The affected job_run rows show attempt = 1, status = succeeded, one started_at, and a lease_owner naming a different host from the one whose logs show the job starting. Leases last 30 seconds and are heartbeated every 10 from inside the handler; lease_expires_at is computed on the worker and compared against the database's now(). Find the mechanism, and give a fix that holds even if you cannot fix the clocks.
Approach
- Start from the fact that eliminates the obvious answer. attempt = 1 means no retry was recorded, so this is not a re-run after failure; two workers ran the same row concurrently and the takeover path never touched the counter. lease_owner naming a host other than the one that started the job is the same statement from the other side.
- Enumerate the mechanisms that cause a premature takeover, then find the signal that separates them. Either the lease genuinely expired because the heartbeat did not fire, which is what happens when the heartbeat runs on the handler's own thread and the handler makes a long blocking call, or it only appeared expired because two clocks disagree, since lease_expires_at is written from the worker's clock and evaluated against the database's. The discriminator is the distribution: incidents clustered on the longest exports indict the heartbeat, incidents clustered on one host indict skew. Measure both, and measure each host's offset against the database directly.
- Read the reclaim query precisely. In PostgreSQL now() is transaction start time, not statement time, so a reclaimer holding a long transaction compares against an older timestamp than expected; clock_timestamp() is the statement-time function. This is worth ruling in or out before you redesign anything, because it changes which rows look expired.
- Remove the second clock rather than trying to synchronise it. Issue and extend the lease in the database, with lease_expires_at = now() + interval '30 seconds' in both the claim and the heartbeat, so exactly one clock is ever compared and worker skew stops mattering to this predicate.
Follow-up
- The displaced worker has already streamed half the file to object storage. What makes that side effect safe to repeat?
- You now count takeovers. What alert fires on that counter, and at what threshold?
Built from the rounds and topics LevelUp candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the LevelUp loop
- Write out the reported sequence: Recruiter Screen, Technical Assessments, Onsite Visit.
- 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 Algorithmic Problem Solving
- Spend the session on Algorithmic Problem Solving, which LevelUp candidates report being tested on.
- Write one worked example in Algorithmic Problem Solving and time yourself on it.
Deliverable: One timed worked example in Algorithmic Problem Solving.
03Work RESTful APIs
- Spend the session on RESTful APIs, which LevelUp candidates report being tested on.
- Write one worked example in RESTful APIs and time yourself on it.
Deliverable: One timed worked example in RESTful APIs.
04Work High-Level System Design
- Spend the session on High-Level System Design, which LevelUp candidates report being tested on.
- Write one worked example in High-Level System Design and time yourself on it.
Deliverable: One timed worked example in High-Level System Design.
05Answer out loud: Coding and Algorithms
- Answer aloud, timed: Write a function to determine if a string is a palindrome.
- Answer aloud, timed: Find the largest palindrome from the product of two 3-digit numbers.
Deliverable: Spoken answers to 2 reported Coding and Algorithms question(s), under time.
06Answer out loud: Technical and System Design
- Answer aloud, timed: Read through existing production code and explain the design.
- Answer aloud, timed: Write a RESTful app that can accept and parse log data.
Deliverable: Spoken answers to 2 reported Technical and System Design question(s), under time.
07Answer out loud: Behavioral and Role Fit
- Answer aloud, timed: Why are you interested in this position at LevelUp?
- Answer aloud, timed: Tell me about your previous programming experience.
Deliverable: Spoken answers to 2 reported Behavioral and Role Fit 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.
Why are you interested in this position at LevelUp?
Why are you interested in this position at LevelUp?
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?
Tell me about your previous programming experience.
Tell me about your previous programming experience.
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 testing your own code?
How do you approach testing your own code?
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
Why are you interested in this position at LevelUp?
- 02
Tell me about your previous programming experience.
- 03
How do you approach testing your own code?
How difficult are the technical interviews?
The difficulty is generally considered average, but the expectation for code quality and testing is high. You should focus on writing clean, idiomatic code rather than just trying to find a "clever" solution.
LevelUp Software Engineer candidate reports ↗What is the best way to prepare for the onsite?
Prepare by reviewing your past projects, brushing up on standard algorithms, and practicing explaining your design decisions out loud. The onsite is a mix of technical and personal sessions, so be ready to talk about how you work as a team member.
LevelUp Software Engineer candidate reports ↗Is there a specific culture I should be aware of?
LevelUp values engineers who are proactive and communicative. The team is often small, meaning your individual impact is high and your ability to work well with others is just as important as your technical skill.
LevelUp Software Engineer candidate reports ↗How long is the typical process?
The duration can vary. While the recruiter will provide a timeline, be prepared for some variability. Always follow up if you have not heard back within the specified window.
LevelUp Software Engineer candidate reports ↗What topics does LevelUp test in interviews?
LevelUp interviews most often cover Algorithmic Problem Solving, Sales Pitch (5-minute pitch), RESTful APIs, Value Proposition Development, and High-Level System Design. The exact emphasis depends on the specific role you apply for.
LevelUp 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.
- 01LevelUp 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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