Exxact · Software Engineer
Updated · 2026-09-24

Exxact Software Engineer
Interview Questions & Guide 2026

THE 60-SECOND BRIEF

As a Software Engineer at Exxact, you are at the intersection of high-performance computing and client-focused engineering. You will contribute to the development and maintenance of robust enterprise systems, including server architectures and custom computing solutions. Your work is critical in ensuring that Exxact continues to deliver specialized hardware and software configurations that meet the rigorous demands of their clients.

The shape of the workload matters more for your prep than the industry label does. Read-heavy serving, write-heavy ingestion and scheduled batch processing have different binding constraints and fail in different places, so find out which one the team lives in before picking design topics.

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

Scope every query and cache key by tenantEvolve APIs without breaking pinned SDK clientsKeep money in integer minor units

30 min read

Browse Software Engineer questions

See the practice prompts

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

As a Software Engineer at Exxact, you are at the intersection of high-performance computing and client-focused engineering. You will contribute to the development and maintenance of robust enterprise systems, including server architectures and custom computing solutions. Your work is critical in ensuring that Exxact continues to deliver specialized hardware and software configurations that meet the rigorous demands of their clients.

This role requires more than just pure coding ability; it demands a blend of technical expertise and a service-oriented mindset. You will often engage with complex system requirements and, at times, interface with the technical implications of customer-facing solutions. Success in this position means you are capable of translating high-level technical challenges into reliable, scalable software while maintaining a high standard of precision and detail.

01

Initial Screening

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

Technical Assessment

reported

Input bounds are the part of the prompt most often skimmed, and they usually contain the answer. They tell you which complexity class is admissible, which narrows the search before you have thought about the problem itself. As a rough planning figure, a compiled language does on the order of 10^8 simple operations per second and an interpreted one roughly an order of magnitude less. So n up to about twenty admits enumerating subsets, a few thousand admits a quadratic pass, and a million admits neither: you need near-linear, or linear with a log factor. If the bounds are missing, ask for them.

What to demonstrate

  • Whether the approach is justified by the stated input size rather than by whichever pattern you recognised first
  • Whether you ask about the properties that change the algorithm: whether the input arrives sorted, whether duplicates occur, whether values are bounded integers, whether it all fits in memory
  • Whether you can name the bottleneck in your own solution and what would remove it, even when you deliberately leave it in place
  • Whether a claimed speedup is real, since memoising a recursion only helps when subproblems genuinely overlap and the state can be keyed cheaply

How to prepare

  • For each algorithm you rely on, write down the largest n it handles in roughly a second, then check two of those figures by timing them in the language you will actually type in
  • For two weeks, write one line naming your target complexity and the bound that justifies it before you write any code, then compare that line with what you ended up submitting
  • Practise the conversion backwards: given a required O(n log n), list the mechanisms that get you there (sorting, a heap, an ordered map, divide and conquer) and choose by what the problem needs to query, not by what you used last
PracHub interview research ↗
03

HR Final Round

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

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

Checking a quota with a select and then writing

Under read-committed isolation, two concurrent transactions both observe a count below the limit and both insert, so the limit is exceeded by exactly the concurrency. Repeatable read does not rescue it either: it provides a stable snapshot, and this is write skew, which snapshot isolation permits by design. The options are serialisable isolation, which detects the conflict and aborts one transaction with a serialisation failure and therefore obliges the caller to retry; a single statement with the predicate inside the write; or a constraint that makes the surplus insert fail outright. The reason this pattern survives review is that it is correct in every test that runs one request at a time.

03

Assuming the input fits in memory

Ask how large the input is in bytes before committing to an in-memory algorithm; beyond that point the options are a single streaming pass, an external sort with bounded buffers, or a sketch that trades exactness for constant memory. An algorithm that assumes random access to the whole input is a different algorithm from one that sees each element once.

04

Answering a debugging question with a guess instead of a bisection

Give a procedure that halves the search space at each step: confirm the symptom reproduces, establish the last known-good version, input or timestamp, then bisect over commits, over the data, or over the layers of the request path. A plausible cause with no way to confirm it is the same move whether it happens to be right or wrong, which is why it scores nothing.

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

How would you approach a linked list implementation or manipulation ta…

medium
data structures and algorithms

How would you approach a linked list implementation or manipulation task?

Approach
  1. Name the brute-force solution and its complexity before improving on it.
  2. Restate the input: its shape, its size, and what is guaranteed about it.
  3. State the target complexity and say which constraint rules the naive version out.
Follow-up
  • Which test case would catch an off-by-one here?
  • How does this change if the input no longer fits in memory?

Can you explain how you apply Object-Oriented Programming (OOP) princi…

medium
data structures and algorithms

Can you explain how you apply Object-Oriented Programming (OOP) principles in your code?

Approach
  1. Name the brute-force solution and its complexity before improving on it.
  2. Walk one small example through your approach before writing the whole thing.
  3. Restate the input: its shape, its size, and what is guaranteed about it.
Follow-up
  • What is the worst case, and how likely is it on real data?
  • Which test case would catch an off-by-one here?

Can you solve medium-level problems involving arrays?

medium
data structures and algorithms

Can you solve medium-level problems involving arrays?

Approach
  1. Walk one small example through your approach before writing the whole thing.
  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?
  • What is the worst case, and how likely is it on real data?

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.

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.

Where do you see yourself with the company in five years?

medium
behavioural and engineering judgement

Where do you see yourself with the company in five years?

Approach
  1. Name the disagreement and how you resolved it with evidence.
  2. Give the blast radius: what could have broken, and what you measured.
  3. Pick a story where you made the decision, not one where you watched it.
Follow-up
  • What did you decide not to do, and why?
  • How did you know your change caused the improvement?

Can you walk me through your past work history and specific project ex…

medium
behavioural and engineering judgement

Can you walk me through your past work history and specific project experiences?

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

What is your experience with enterprise servers and BDUs?

medium
behavioural and engineering judgement

What is your experience with enterprise servers and BDUs?

Approach
  1. Name the disagreement and how you resolved it with evidence.
  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
  • What did you decide not to do, and why?
  • What would you do differently if you ran that again?
  • 01

    Where do you see yourself with the company in five years?

  • 02

    Can you walk me through your past work history and specific project experiences?

  • 03

    What is your experience with enterprise servers and BDUs?

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

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

PracHub interview research ↗
How long does the entire interview process usually take?

The process typically moves through three rounds. While it can vary, most candidates move through these stages within a few weeks.

PracHub interview research ↗
What is the best way to prepare for the technical round?

Review your fundamentals in data structures and OOP. Ensure you can code simple to medium-level algorithms on a whiteboard or shared document without relying on IDE autocompletion.

PracHub interview research ↗
Is the culture at Exxact collaborative or individualistic?

The culture emphasizes technical precision and problem-solving. While you will work independently on code, you must be able to communicate effectively with other departments to ensure the success of the systems you support.

PracHub interview research ↗
What differentiates a successful candidate?

Successful candidates are those who show a strong balance between technical depth and a professional, customer-focused attitude. Being able to explain your past work clearly is just as important as solving the technical problems presented.

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.