Kentro · Software Engineer
Updated · 2026-09-24

Kentro Software Engineer
Interview Questions & Guide 2026

THE 60-SECOND BRIEF

As a Software Engineer at Kentro, you are at the intersection of technical innovation and operational efficiency. This role is critical to the company’s mission, as it involves building and maintaining the platforms and automation tools that drive customer service excellence and internal workflow optimization. Whether you are working on ServiceNow Citizen Development or Platform Engineering, your contributions directly impact how the organization scales its digital infrastructure.

The loop does not sample the job evenly, and arguing about that in the room costs you. Daily work is mostly incremental change inside code someone else wrote, while the loop samples narrow slices of it; prepare for the slices and save the realism argument for your questions at the end.

Kentro candidates report 2 rounds · ≈ 2-4 weeks. The stages below are what candidates describe, not a published process.

Bound blast radius with per-tenant concurrency limitsMake every write idempotent under client retriesScope every query and cache key by tenant

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See the practice prompts

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

As a Software Engineer at Kentro, you are at the intersection of technical innovation and operational efficiency. This role is critical to the company’s mission, as it involves building and maintaining the platforms and automation tools that drive customer service excellence and internal workflow optimization. Whether you are working on ServiceNow Citizen Development or Platform Engineering, your contributions directly impact how the organization scales its digital infrastructure.

You will be tasked with solving complex problems, from creating virtual agents to streamlining enterprise automation. This position is not just about writing code; it is about understanding the business challenges behind the technology and delivering robust, scalable solutions. You can expect a high-paced, challenging environment where your ability to translate technical requirements into functional, user-centric software is highly valued.

01

Recruiter Call

reported

Half of this call is the part candidates treat as small talk: start date, notice period, work authorisation and its timing, location and time zone, on-call, and the number. Those are what kill offers late, after several engineers have each spent a day. Surfacing a hard constraint now costs you nothing and occasionally buys you something, since a loop compressed to fit a competing deadline can usually only be arranged if it is asked for early. The common failure is deflecting the compensation question twice, then discovering at offer stage that the band never reached your number.

What to demonstrate

  • Whether your hard constraints are compatible with the role before a loop gets booked: earliest start, notice period, what authorisation you hold and when it needs action, days on site, willingness to carry a pager
  • Whether you give a compensation range with something behind it, such as current total compensation or a competing timeline, rather than leaving the band untested
  • Whether your stated timeline is real, since a competing deadline raised now is something scheduling can sometimes work around and the same deadline raised at offer stage usually is not

How to prepare

  • Write each constraint down in one line before the call and state them as facts rather than negotiating them live under a question you were not expecting
  • Set your range from two or three current data points for that level and location, and name the structure you are quoting in, so the number is comparable to the one they are holding
  • If another process is running, say where it stands and by when, and ask directly whether this loop can be scheduled inside that window
PracHub interview research ↗
02

Engineering Team Session

reported

An unlabelled round is first an information problem, and the cheapest information is free. Whoever schedules it can usually tell you how long it runs, who will be in the room and what they work on, whether you will be writing code and in what environment, and whether anything is being sent beforehand. Ask in writing so the answer is on record, then prepare for the two or three formats those answers still leave open instead of betting on one. What separates a strong candidate is not guessing right; it is having an opening that works whichever one it turns out to be.

What to demonstrate

  • Whether you can start work from an ambiguous brief, since tolerating a vague scope without stalling is the same thing the job asks for
  • Whether the questions you asked beforehand were ones that change your preparation, such as duration, medium and who is joining, rather than ones whose answers you could not have acted on
  • Whether you adapt when the round turns out to be something other than what you were told, instead of spending the first ten minutes visibly recalibrating

How to prepare

  • Send one short scheduling message asking four things: how long, who is joining and what they work on, whether you will be writing code and where, and whether to prepare anything in advance. Treat a vague reply as real information, since it means the round is loosely structured and you will be shaping it yourself.
  • Write one opening that works in any of the formats still open: restate in your own words what you have been asked to do, then ask which of two directions is more useful to them. Say it aloud until it stops sounding recited.
  • Set up for the two most likely formats before the call starts, with a blank editor in the language you would choose and a shared document you can type into, so a format surprise costs you nothing in the first minutes
PracHub interview research ↗

PracHub editorial advice for the preparation topics above.

01

Holding money in a floating-point type, or rounding it more than once

Binary floating point cannot represent 0.01 or 0.1 exactly, so sums drift and two code paths that should agree disagree by cents nobody can trace back. The fix is integer minor units or an exact decimal type end to end, with sub-cent rates expressed as scaled integers such as micro-units, because a per-request price genuinely is smaller than a cent. The second half of the trap is rounding position: rounding each line and then summing gives a different total from summing and rounding once, and half-up and half-even diverge systematically across many lines, so rounding must happen at one named place and every downstream reader must carry the rounded value rather than recompute it from quantity and rate.

02

Serialising a tenant's writes through select ... for update on a single counter row

It is the first change that makes a counter correct, and it caps that tenant's write throughput at roughly one divided by the lock hold time. A transaction that takes the lock, makes a network call and then commits holds it for the entire round trip: at 2 ms that is about 500 writes per second for the whole tenant, and the largest tenants are exactly the ones that exceed it. The damage then spreads, because every waiter holds a database connection while it queues, so one hot tenant drains the shared pool and the symptom presents as a site-wide latency incident rather than as a lock problem. The repairs are to shrink the critical section to a single statement, to shard the counter into per-(tenant, hour) or per-(tenant, bucket) rows and sum on read, or to batch in memory and flush periodically while accepting the bounded loss that batching implies.

03

Writing code before the input contract is pinned down

Before the first line, state the types, the size bounds, whether duplicates, negatives or an empty input are possible, whether the input is sorted, whether you may mutate it, and what the function returns when nothing matches. Every one of those answers changes the code, and discovering one at minute twenty costs a rewrite you no longer have time for.

04

Retrying a write that is not safe to repeat

A timeout tells you nothing about whether the server applied the write, so a blind retry of a create or a charge can duplicate it. Either make the operation idempotent, with a caller-supplied key the server deduplicates on or a conditional update, or do not retry it; and use exponential backoff with jitter so the retries of many clients do not synchronise into a second outage.

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

10 technical prompts3 include a worked solution

Describe your process for testing and validating your solutions.

medium
data structures and algorithms

Describe your process for testing and validating your solutions.

Approach
  1. State the target complexity and say which constraint rules the naive version out.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
Follow-up
  • How does this change if the input no longer fits in memory?
  • Which test case would catch an off-by-one here?

Walk me through your approach to solving [specific coding challenge].

medium
data structures and algorithms

Walk me through your approach to solving [specific coding challenge].

Approach
  1. State the target complexity and say which constraint rules the naive version out.
  2. Restate the input: its shape, its size, and what is guaranteed about it.
  3. Walk one small example through your approach before writing the whole thing.
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 balance speed of delivery with code quality?

medium
data structures and algorithms

How do you balance speed of delivery with code quality?

Approach
  1. Choose the data structure from the access pattern, not from familiarity.
  2. State the target complexity and say which constraint rules the naive version out.
  3. Name the brute-force solution and its complexity before improving on it.
Follow-up
  • What is the worst case, and how likely is it on real data?
  • How does this change if the input no longer fits in memory?

Parse and verify a timestamped multi-signature webhook header

easyWorked solution
parsinghmacconstant-time-comparereplay-protection

An inbound webhook carries a signature header of at most 1 KiB shaped t=<unix seconds>,v1=<64 hex chars>, with up to five v1 values during secret rotation and possibly unknown scheme keys. You hold the raw request body bytes and the currently active signing secrets. Write the parser and the verifier: accept when any active secret reproduces a signature and the timestamp is within a five-minute tolerance in either direction, reject otherwise. Single left-to-right pass over the header, no regular expression. State what is inside the MAC and why.

Approach
  1. Parse in one scan: split on ,, then on the first = only, since a value may itself contain = under a future scheme. Accept t exactly once and treat a second t as a reject rather than last-wins. Push every v1 onto a short list and ignore any other key, so a v2 can be introduced later without breaking this verifier.
  2. Say what is signed: HMAC-SHA256 over the exact byte string <t>.<raw body bytes>, yielding 32 bytes or 64 hex characters. The timestamp sits inside the MAC because otherwise an attacker replays yesterday's body with its still-valid signature and only has to edit the header timestamp.
  3. Hash the bytes as received. Verifying against a re-serialised JSON body is the usual defect: key order, whitespace and number formatting all change the bytes while the parsed objects compare equal, so signatures fail for honest senders and the popular 'fix' is to stop checking.
  4. Compare in constant time over fixed-length digests. Decode the hex to 32 bytes, accumulate acc |= a[i] ^ b[i] across the whole length, and test acc == 0 at the end. Evaluate every candidate without an early exit; at five candidates that is five HMACs over the body, linear in body size and negligible beside the network.
  5. Apply the tolerance as a two-sided bound, rejecting when |now - t| > 300 seconds. A sender whose clock runs ahead of yours is an ordinary case, and an unbounded future timestamp is a free replay window.
  6. Complexity: O(L) over the header producing k candidates, plus k HMACs at O(|body|) each. Space is O(k) beyond the body itself. Do the cheap rejections, including the tolerance check, before any cryptography runs.
Worked solution 15 min
  1. Write the grammar on one line before coding: header := field (',' field)*, field := key '=' value, split on the first = only.
  2. Implement the parser to return {t: int, v1: [hex, ...]}, rejecting a missing t, a duplicate t, any v1 that is not 64 hex characters, and a header over 1 KiB, all before any cryptography runs.
  3. Implement the verifier: for each active secret compute HMAC-SHA256(secret, f'{t}.'.encode() + raw_body), compare it in constant time against each parsed v1, and OR the results with no early exit.
  4. Test with a valid signature; the same body with t moved 400 seconds into the past; the same body with t 400 seconds into the future; a header carrying an unknown v2= alongside a valid v1; and a body re-serialised with different JSON key order.
EXPECTED RESULTThe valid case accepts. Both out-of-tolerance cases reject, including the future one. The unknown `v2` field is ignored and the `v1` still verifies. The re-serialised body fails, which is correct and is exactly why the raw bytes must be retained.
Follow-up
  • The body is 40 MB. What changes about where you verify, and what can you do before the whole body has arrived?
  • A customer reports that signatures fail for exactly the requests whose body contains a non-ASCII character. What is your first hypothesis?
  • How do you rotate the signing secret with no failed deliveries, and how long do both secrets stay live?

Day one measures instead of guessing, under a fixed rubric, and the remaining hours are allocated in proportion to the gaps before any studying begins. The allocation is deliberately not renegotiated midweek, because the area that feels worst on day three is usually the one that is moving.

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
01Diagnostic, scored before you study anything
  • Sit a 110-minute diagnostic in four blocks: forty-five minutes on two coding problems, twenty-five on one design prompt taken to interface and data model, twenty of short-answer fundamentals, and twenty delivering two behavioural answers aloud.
  • Score each block from 0 to 3 on a fixed rubric where 3 is correct and fluent, 2 is correct but slow or prompted, 1 is partially correct and 0 is stuck, grading the artifact rather than how the attempt felt.
  • Allocate days two to five in proportion to 3 minus each block's score, write the allocation down, and commit to leaving it alone.

Deliverable: A scored rubric and a fixed hour allocation for the rest of the week.

Practice prompt ↗Practice prompt ↗Worked solution ↗
02Largest gap: find the boundary rather than the subject
  • Split the weakest area into named sub-skills and rate each separately. For coding those are restating the problem, choosing the structure, stating the invariant, turning the invariant into loop bounds, handling empty and single-element input, and accounting for complexity out loud.
  • Attempt three items positioned just above where the rating drops off, and for each write the first move you failed to make.
  • Re-attempt one of them from blank four hours later with nothing open.

Deliverable: A sub-skill map with the two blocking sub-skills circled.

Practice prompt ↗Practice prompt ↗
03Drill the blocking sub-skill by repeating the shape
  • Do eight short repetitions of the same shape rather than eight different problems, so what gets practised is the pattern and not the puzzle.
  • State the rule you now hold in one sentence, then test it against a case built to break it, a sliding window over an array containing negative values, or a cache-aside read path whose invalidation message is dropped.
  • Have someone else read your one-sentence rule and find the precondition you left out.

Deliverable: One rule statement with its preconditions attached and one counterexample that would have caught the incomplete version.

Practice prompt ↗Practice prompt ↗
04Second gap, plus maintenance on the strongest area
  • Run the same sub-skill decomposition on the second-largest gap in half the time.
  • Spend twenty-five timed minutes on the block you scored highest, choosing the hardest item you can still finish rather than a warm-up.
  • Write whether each area fails you on recall, on setup, or on execution, and set the fix accordingly: repetition for recall, a written checklist for setup, timed work for execution.

Deliverable: A second sub-skill map plus a one-line failure diagnosis for each area.

Practice prompt ↗Practice prompt ↗Worked solution ↗
05The gap that is not a skill
  • Record one technical and one behavioural answer, then count two things in the playback: seconds before your first clarifying question, and sentences you began without knowing where they would end.
  • Practise saying that you do not know, followed by how you would find out, without letting it soften into a guess, and practise stating a complexity or an estimate before being asked for it.
  • Redeliver one answer under a hard ninety-second cap, which forces structure ahead of detail.

Deliverable: Two recordings with a counted reduction in time-to-first-question.

Practice prompt ↗Practice prompt ↗
06Retest under day-one conditions
  • Sit the same 110-minute structure with new prompts of comparable difficulty and score it on the identical rubric.
  • For any block that did not move, change the method rather than adding hours: a block stuck at 1 usually means the practice was too varied, not too short.
  • Write down which single block you would still lose the offer on.

Deliverable: A second scored rubric placed beside the first, with one named remaining risk.

Practice prompt ↗Practice prompt ↗
07Full loop under interview conditions
  • Run a sixty-minute mock over the two blocks that moved least, with an interviewer briefed to interrupt and change direction mid-answer.
  • Write the recovery script for going blank: restate the question, state your assumption, name the first thing you would check.
  • Say every rule from the week aloud without reading it, and cut any you cannot state in a single sentence, since a rule you have to reconstruct mid-answer will not survive an interruption.

Deliverable: A one-page card holding the recovery script and only the rules you could state from memory.

Practice prompt ↗Worked solution ↗

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

Counting review comments or mentees proves nothing. The useful version is a specific change you approved with a reservation you stated, or one you blocked and the delay that cost. Say which standard you were holding and why it was worth the friction. A mentoring story needs the thing the other person can now do without you.

How do you handle ambiguity when given a vague technical requirement?

medium
behavioural and engineering judgement

How do you handle ambiguity when given a vague technical requirement?

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

Can you walk me through a time you had to debug a complex system issue…

medium
behavioural and engineering judgement

Can you walk me through a time you had to debug a complex system issue?

Approach
  1. Pick a story where you made the decision, not one where you watched it.
  2. Close with what you would do differently, concretely.
  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?

What is your experience with ServiceNow or similar automation platform…

medium
behavioural and engineering judgement

What is your experience with ServiceNow or similar automation platforms?

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
  • How did you know your change caused the improvement?
  • What would you do differently if you ran that again?
  • 01

    How do you handle ambiguity when given a vague technical requirement?

  • 02

    Can you walk me through a time you had to debug a complex system issue?

  • 03

    What is your experience with ServiceNow or similar automation platforms?

PracHub interview preparation framework ↗
Is this an official Kentro interview guide?

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

PracHub interview research ↗
Is the technical interview very difficult?

It is challenging but fair. The interviewers are less interested in "gotcha" questions and more interested in how you approach complex, real-world engineering problems.

PracHub interview research ↗
How much time should I spend preparing?

Dedicate at least one to two weeks to reviewing your past projects and practicing coding challenges. Being able to talk through your experience fluently is just as important as technical accuracy.

PracHub interview research ↗
What is the culture like at Kentro?

The culture is fast-paced and results-oriented. Engineers are expected to take ownership of their work and contribute to the overall success of the product.

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

It varies, but from the initial recruiter call to the final interview, it is designed to be efficient. Ensure you respond promptly to scheduling requests to keep the momentum going.

PracHub interview research ↗
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.