As a Software Engineer at Siteimprove, you play a pivotal role in maintaining and evolving the digital experience platform that empowers organizations to achieve accessibility, SEO, and performance excellence. You are not just writing code; you are building the infrastructure that helps thousands of global companies ensure their digital content is inclusive, compliant, and high-performing. Your work directly impacts how users interact with the web, making the internet a better place for everyone. This position demands a blend of technical rigor and a deep sense of ownership. You will work within cross-functional teams, collaborating closely with product managers and fellow engineers to solve complex challenges related to data processing at scale and intuitive user interface development. Whether you are optimizing backend services or refining frontend components, you are contributing to a product suite that prides itself on precision and reliability. Expect to work in an environment that values innovation but demands practical, high-quality implementations. You will be challenged to think critically about system architecture and the long-term maintainability of your solutions. It is an ideal role for engineers who are passionate about web standards and want to see their contributions have a tangible, measurable impact on the digital landscape.
Recruiter Screen
reportedInitial conversation to align on your background and interest in the position.
What to demonstrate
- Initial conversation to align on your background and interest in the position
- Depth in Take-home coding assignment
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 Evaluation
reportedAssessment that may include a take-home assignment or a live coding session.
What to demonstrate
- Assessment that may include a take-home assignment or a live coding session
- Depth in Take-home coding assignment
How to prepare
- Answer aloud and timed: How do you handle edge cases when building data-intensive applications?
- Answer aloud and timed: What is your process for reviewing a peer’s code to ensure it meets quality standards?
Interviews with Managers
reportedConversations with hiring managers and developers to assess fit and technical skills.
What to demonstrate
- Conversations with hiring managers and developers to assess fit and technical skills
- Depth in Take-home coding assignment
How to prepare
- Answer aloud and timed: Can you explain the trade-offs between different data structures for a specific problem?
- Answer aloud and timed: Describe a time you disagreed with a technical decision made by your team. How did you resolve it?
PracHub editorial advice for the preparation topics above.
Research the Product
Understand what Siteimprove actually does. Familiarize yourself with their accessibility and SEO tools before your first interview.
Own Your Background
Be prepared to speak confidently about every item on your CV. If you have a background in a specialized area like machine learning, be ready to explain its practical application.
Ask Strategic Questions
Use your interview time to ask about the team’s current technical debt, the deployment process, and how they balance feature work with platform stability.
Be Professional
Maintain a high level of professionalism in all interactions. The interviewers are evaluating whether you would be a good colleague to work with daily.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Explain how you would approach a take-home coding assignment to ensure readability and maintainability.
Explain how you would approach a take-home coding assignment to ensure readability and maintainability.
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?
What is your process for reviewing a peer’s code to ensure it meets quality standards?
What is your process for reviewing a peer’s code to ensure it meets quality standards?
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?
Can you explain the trade-offs between different data structures for a specific problem?
Can you explain the trade-offs between different data structures for a specific problem?
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?
Why do you want to join Siteimprove specifically, rather than another tech company?
Why do you want to join Siteimprove specifically, rather than another tech company?
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- Handle the rows that do not match: that is usually the actual question.
Follow-up
- How does the query change if that join becomes one-to-many?
- What happens to this when the table is ten times larger?
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?
Specify the outbound webhook contract a customer endpoint can verify
Egress delivery sends resource.created, resource.updated and resource.archived to roughly 40k customer endpoints at about 1.5k deliveries/second, with a per-destination concurrency cap of 4 and a 10 second connect-plus-read timeout, at-least-once from the relay. The receiver is code you do not control, often behind a proxy that may re-encode JSON. Specify the payload envelope, how the receiver verifies authenticity and rejects replays, what ordering it may assume, how it deduplicates, which status codes it should return and what each means to us, and the retry, circuit and replay behaviour.
Approach
- Send the fact, not a pointer: event_id, event_type, aggregate_type, aggregate_id, aggregate_version, occurred_at and the payload copied from outbox_event. A receiver told only that resource 42 changed has to call back, and the call back returns a newer state than the event describes - that is precisely how a consumer applies changes out of order while believing it is following them.
- Sign the exact bytes on the wire: HMAC-SHA256 over the timestamp, a separator, and the raw body, in a header, compared in constant time before the body is parsed. Instruct receivers to verify the raw bytes, never a re-serialised copy, since a proxy that reorders keys or changes whitespace invalidates a signature computed over re-encoded JSON. Reject a timestamp outside a tolerance - five minutes is typical - and keep a short seen-set of event_ids, because a capture replayed inside the tolerance still verifies.
- Support key rotation by sending several signature values in one header during the overlap window and publishing that any one that verifies is sufficient. Without that rule a key rotation is a synchronised outage across every destination at once.
- State the guarantee as it actually is: at-least-once and unordered, including within a single aggregate_id. The outbox is ordered per aggregate at the source, but the relay holds up to 4 requests in flight per destination and backs off each retry independently, so a version 6 delivery that needs one retry lands after a version 7 that succeeded on its first attempt. Publishing per-aggregate ordering we do not enforce is worse than publishing none, because a receiver that trusts it overwrites new state with old. Receivers deduplicate on event_id and apply conditionally - UPDATE ... WHERE aggregate_version < :incoming, or the same comparison under a row lock on the aggregate - which discards stale redeliveries and stays correct when two deliveries for one aggregate are processed at the same time. A duplicate and an out-of-order delivery then have the same outcome: no-op.
Follow-up
- A customer insists an event never arrived. What do you check, in order, and which table settles the argument?
- A receiver cannot store a version and asks us to deliver their events in order. What would the relay have to give up to offer that, and what does one failing event then do to the rest of their stream?
Relay committed events to the log without gaps or reordering
outbox_event rows are written in the same transaction as the state change and carry aggregate_type, aggregate_id, aggregate_version, payload and status, with a partial index on (created_at, event_id) WHERE status = 'pending'. The relay publishes about 4k events/second to a partitioned append-only log keyed by aggregate_id, with one leader per partition range holding a lease. Consumers must never miss an event; they may see one twice. Design the claim-publish-mark loop, and state exactly what consumers observe when a leader's lease expires while it is mid-batch.
Approach
- Claim with SELECT ... WHERE status='pending' ORDER BY created_at, event_id LIMIT $batch FOR UPDATE SKIP LOCKED inside a transaction. SKIP LOCKED lets several relay workers share a range without serialising on each other's rows, and the partial index keeps the claim proportional to the backlog rather than to a table that is overwhelmingly published rows. At 4k/second a batch of 500 is eight claims per second, each an index scan of 500 entries.
- Publish before marking, never the reverse, and say why it is a choice. Marking first loses the event outright if the process dies in the gap, and the loss is silent - nothing remains to retry, and it surfaces later as a projection missing a row. Publishing first can repeat the event, and repetition is what every consumer is already built to survive. That single ordering is the whole at-least-once guarantee.
- Preserve the only ordering on offer. Partition by aggregate_id and never publish two events for one aggregate concurrently: claim in (created_at, event_id) order and publish sequentially within an aggregate, or hash aggregate_id to a worker slot. Order across aggregates is not available at any price here, which is why the event carries aggregate_version and the full fact rather than a delta - a consumer can then discard what it has already applied without coordinating with anyone.
- State the failover behaviour precisely, because it is the consistency-versus-availability decision in this design. A lease expires because the holder is slow, and no mechanism distinguishes that from dead, so for the length of the lease window two leaders can publish the same claimed batch. The system accepts duplicates to avoid stalling publication for every aggregate in the range whenever one worker pauses. Consumers deduplicate on (aggregate_id, aggregate_version) and drop anything at or below what they have applied.
Follow-up
- The relay is down 40 minutes and 9.6 million rows are pending. What does catch-up do to the primary, and what changes in the claim loop to survive it?
- A consumer insists it never received an event. Which single query settles whether the relay lost it, and what does each answer look like?
Every query on one table stalls for forty seconds mid-deploy
During a release on PostgreSQL, every query touching resource times out for about 40 seconds and then recovers with no intervention. The release ran one migration, ALTER TABLE resource ADD COLUMN archived_reason TEXT, and the migration log shows it completing in 6 ms. Unrelated tables showed no change in error rate. Explain how a 6 ms statement caused a 40-second stall, give the ordered checks you would run on a live system to confirm it, and give the migration procedure that prevents a repeat.
Approach
- Separate the statement's duration from the lock's duration. ADD COLUMN with no default is a catalogue-only change and genuinely runs in milliseconds, but it requires ACCESS EXCLUSIVE, and it cannot acquire that until every transaction already touching the table has finished.
- Account for the queueing, which is the part that surprises people. A lock request that is waiting blocks later requests for conflicting modes behind it rather than letting them overtake, so one long-open transaction holds the DDL and the DDL holds all the traffic. The stall length is set by the longest open transaction, not by the size of the change.
- Confirm on a live system in this order: pg_stat_activity for that table ordered by xact_start, looking for the oldest transaction and specifically for state = idle in transaction; then pg_locks where granted = false to find the waiter; then join them on pid to name blocker and blocked. pg_blocking_pids() does that join for you and is the fastest single call.
- Prevent rather than merely time it better. Set lock_timeout to a second or two on the migration session so the DDL abandons the queue after a bounded wait and is retried, instead of holding it for as long as the oldest transaction lives. Be exact about what that buys: queries arriving during the wait still queue behind the pending ACCESS EXCLUSIVE request, so each attempt costs them up to one lock_timeout of added latency. The outage goes from 40 seconds to about one second per attempt, not to zero. Also run migrations away from deploy-time peaks, and put a statement timeout and an idle-in-transaction timeout on the analytics role that opens the long transactions.
Follow-up
- The same release also wants NOT NULL on that column. What is the sequence that gets there without a long lock?
- Your lock_timeout retry fails ten times in a row because the analytics transaction is always open. What do you change?
Built from the rounds and topics Siteimprove candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Siteimprove loop
- Write out the reported sequence: Recruiter Screen, Technical Evaluation, Interviews with Managers.
- 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 Take-home coding assignment
- Spend the session on Take-home coding assignment, which Siteimprove candidates report being tested on.
- Write one worked example in Take-home coding assignment and time yourself on it.
Deliverable: One timed worked example in Take-home coding assignment.
03Work Git and version control
- Spend the session on Git and version control, which Siteimprove candidates report being tested on.
- Write one worked example in Git and version control and time yourself on it.
Deliverable: One timed worked example in Git and version control.
04Work Programming problem solving (coding interviews)
- Spend the session on Programming problem solving (coding interviews), which Siteimprove candidates report being tested on.
- Write one worked example in Programming problem solving (coding interviews) and time yourself on it.
Deliverable: One timed worked example in Programming problem solving (coding interviews).
05Answer out loud: Technical & Coding Proficiency
- Answer aloud, timed: Explain how you would approach a take-home coding assignment to ensure readability and maintainability.
- Answer aloud, timed: Describe a time you had to debug a complex issue in a production environment.
Deliverable: Spoken answers to 2 reported Technical & Coding Proficiency question(s), under time.
06Answer out loud: Behavioral & Cultural Alignment
- Answer aloud, timed: Describe a time you disagreed with a technical decision made by your team. How did you resolve it?
- Answer aloud, timed: Why do you want to join Siteimprove specifically, rather than another tech company?
Deliverable: Spoken answers to 2 reported Behavioral & Cultural Alignment question(s), under time.
07Dry run for Siteimprove
- Run one full mock under time, then write down the two questions you most want to ask your interviewers.
Deliverable: A completed timed mock and two questions to ask.
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.
Describe a time you had to debug a complex issue in a production environment.
Describe a time you had to debug a complex issue in a production environment.
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 handle edge cases when building data-intensive applications?
How do you handle edge cases when building data-intensive applications?
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?
Describe a time you disagreed with a technical decision made by your team. How did you resolve it?
Describe a time you disagreed with a technical decision made by your team. How did you resolve it?
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 a time you had to explain a complex technical concept to a non-technical stakeholder.
Tell me about a time you had to explain a complex technical concept to a non-technical stakeholder.
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 stay updated with emerging technologies and decide which ones are worth adopting?
How do you stay updated with emerging technologies and decide which ones are worth adopting?
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?
Describe a situation where you had to pivot quickly due to changing project requirements.
Describe a situation where you had to pivot quickly due to changing project requirements.
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
Describe a time you had to debug a complex issue in a production environment.
- 02
How do you handle edge cases when building data-intensive applications?
- 03
Describe a time you disagreed with a technical decision made by your team. How did you resolve it?
- 04
Tell me about a time you had to explain a complex technical concept to a non-technical stakeholder.
How long does the interview process typically take?
The timeline can range from a few weeks to a couple of months. It is important to stay proactive and maintain regular contact with your recruiter to understand where you are in the pipeline.
Siteimprove Software Engineer candidate reports ↗What is the most important thing to focus on for the technical assignment?
Focus on clean, readable, and well-structured code. The interviewers are less interested in "clever" one-liners and more interested in how you structure your logic for long-term maintainability.
Siteimprove Software Engineer candidate reports ↗Is there a specific focus on AI or Machine Learning?
While Siteimprove utilizes various technologies, the core of your role will be centered on robust software engineering. Be prepared to discuss your background, but emphasize your core engineering skills first and foremost.
Siteimprove Software Engineer candidate reports ↗What topics does Siteimprove test in interviews?
Siteimprove interviews most often cover Stakeholder Management, Behavioral Interviewing, Problem Solving, Marketing Analytics, and Machine Learning Engineering (Production ML). The exact emphasis depends on the specific role you apply for.
Siteimprove 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.
- 01Siteimprove 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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