As a Software Engineer at Simon AI, you will play a pivotal role in shaping the technology that drives our innovative solutions. Your work will directly impact the efficiency and effectiveness of our products, which serve a diverse clientele seeking to harness data for insightful decision-making. This position is not only crucial for maintaining our competitive edge but also offers the opportunity to engage with complex problems that challenge your technical and creative skills. You will collaborate closely with cross-functional teams, including product managers and data scientists, to design and implement features that enhance user experience and drive business growth. The scale and intricacy of the projects you’ll tackle—ranging from developing robust APIs to optimizing algorithms—make this role both rewarding and intellectually stimulating. At Simon AI, you are not just writing code; you are contributing to a vibrant ecosystem that leverages cutting-edge technology to solve real-world problems.
Initial Phone Screen
reportedThe process begins with a phone screen to assess the candidate's background and fit for the role.
What to demonstrate
- The process begins with a phone screen to assess the candidate's background and fit for the role
- 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 Assessment
reportedCandidates complete a technical assessment, which may include a coding exercise.
What to demonstrate
- Candidates complete a technical assessment, which may include a coding exercise
- Depth in Algorithmic Problem Solving
How to prepare
- Answer aloud and timed: Describe a time when you had to debug a complex issue in your code.
- Answer aloud and timed: How do you handle version control in collaborative projects?
Take-Home Assignment
reportedA take-home assignment is provided to evaluate practical skills relevant to the position.
What to demonstrate
- A take-home assignment is provided to evaluate practical skills relevant to the position
- Depth in Algorithmic Problem Solving
How to prepare
- Answer aloud and timed: What data structures would you use to implement a priority queue?
- Answer aloud and timed: Design a URL shortening service and discuss its architecture.
On-Site Interview
reportedSuccessful candidates participate in an on-site interview with a series of technical and behavioral interviews.
What to demonstrate
- Successful candidates participate in an on-site interview with a series of technical and behavioral interviews
- Depth in Algorithmic Problem Solving
How to prepare
- Answer aloud and timed: How would you approach building a real-time chat application?
- Answer aloud and timed: What considerations would you take into account for a distributed file storage system?
PracHub editorial advice for the preparation topics above.
Practice Coding Under Pressure
Engage in timed coding challenges to simulate the interview environment and build your confidence.
Be Prepared to Explain Your Thought Process
Interviewers will appreciate candidates who articulate their reasoning and approach to problem-solving.
Research Simon AI’s Products
Familiarize yourself with the company’s offerings and recent developments to demonstrate your interest and understanding during interviews.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Can you explain how you would optimize a given algorithm?
Can you explain how you would optimize a given algorithm?
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?
Solve a problem related to binary trees, such as finding the lowest common ancestor.
Solve a problem related to binary trees, such as finding the lowest common ancestor.
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 to detect a cycle in a linked list.
Write a function to detect a cycle in a linked list.
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 sorting algorithm of your choice and explain its time complexity.
Implement a sorting algorithm of your choice and explain its time complexity.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Write the update path that detects a concurrent edit
resource carries version INT NOT NULL DEFAULT 1. resource_revision holds revision_id, resource_id, version, actor_user_id, change_kind, patch JSONB, request_id, created_at with UNIQUE (resource_id, version). outbox_event holds aggregate_type, aggregate_id, aggregate_version, event_type, payload, status. A PUT carries the version the client read. Write the exact statements for the single transaction that applies the edit, records the revision and enqueues 'resource.updated', and give the handler's branch on zero affected rows. Then say what PostgreSQL 16 does under READ COMMITTED when two of these updates hit one row at once.
Approach
- One transaction, three writes, no network call inside it: UPDATE resource SET title = $3, version = version + 1, updated_at = now() WHERE resource_id = $1 AND tenant_id = $4 AND version = $2; then INSERT the resource_revision row at version $2 + 1; then INSERT the outbox_event row at the same aggregate_version. The event goes to a table rather than a broker because no transaction spans both.
- Branch on the affected-row count before doing anything else. Zero has three causes — stale version, wrong tenant, row gone — so re-read once and map to 409 carrying the current version, or 404 for an id outside the caller's tenant, which also stops the endpoint confirming that another tenant's id exists.
- State the engine behaviour instead of assuming it. Under READ COMMITTED the second UPDATE blocks on the row lock, and when the first commits PostgreSQL re-evaluates the WHERE clause against the newly committed row, so the version predicate now fails and the statement reports zero rows. Under REPEATABLE READ the identical collision raises SQLSTATE 40001 instead, so the handler must fold both shapes into one conflict response.
- Keep UNIQUE (resource_id, version) even though the predicate already serialises writers. It is what makes a lost update unwritable if any other path ever reaches the revision table, and it converts a logic bug into 23505 rather than into a silently missing history row.
Follow-up
- A client sends the version it read ten minutes ago and the resource has moved three versions. What is in your 409 so it can resolve the conflict without a full re-fetch?
- Two editors, two disjoint fields, no overlap. Does your answer still refuse the second write, and should it?
Explain why the owner filter ignores the listing index
The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id = $2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.
Approach
- Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
- For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
- Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
- Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.
Follow-up
- 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
- A dashboard runs this for 40 owners in one page load. What changes about the design?
What are the differences between functional and object-oriented programming?
What are the differences between functional and object-oriented programming?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
What data structures would you use to implement a priority queue?
What data structures would you use to implement a priority queue?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Design a URL shortening service and discuss its architecture.
Design a URL shortening service and discuss its architecture.
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
How would you approach building a real-time chat application?
How would you approach building a real-time chat application?
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?
What considerations would you take into account for a distributed file storage system?
What considerations would you take into account for a distributed file storage system?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
How would you handle a situation where a project deadline is at risk?
How would you handle a situation where a project deadline is at risk?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
If given incomplete specifications for a feature, how would you proceed with development?
If given incomplete specifications for a feature, how would you proceed with development?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
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 Simon AI candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Simon AI loop
- Write out the reported sequence: Initial Phone Screen, Technical Assessment, Take-Home Assignment, On-Site Interview.
- For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.
Deliverable: A one-page map of the 4 reported rounds, with the weakest marked.
02Work Algorithmic Problem Solving
- Spend the session on Algorithmic Problem Solving, which Simon AI 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 Take-Home Coding Assignments
- Spend the session on Take-Home Coding Assignments, which Simon AI candidates report being tested on.
- Write one worked example in Take-Home Coding Assignments and time yourself on it.
Deliverable: One timed worked example in Take-Home Coding Assignments.
04Work Coding Interviews (Screen-Share)
- Spend the session on Coding Interviews (Screen-Share), which Simon AI candidates report being tested on.
- Write one worked example in Coding Interviews (Screen-Share) and time yourself on it.
Deliverable: One timed worked example in Coding Interviews (Screen-Share).
05Answer out loud: Technical Questions
- Answer aloud, timed: What are the differences between functional and object-oriented programming?
- Answer aloud, timed: Can you explain how you would optimize a given algorithm?
Deliverable: Spoken answers to 2 reported Technical Questions question(s), under time.
06Answer out loud: System Design
- Answer aloud, timed: Design a URL shortening service and discuss its architecture.
- Answer aloud, timed: How would you approach building a real-time chat application?
Deliverable: Spoken answers to 2 reported System Design question(s), under time.
07Answer out loud: Behavioral Questions
- Answer aloud, timed: Tell me about a time you faced a significant challenge in a project. How did you handle it?
- Answer aloud, timed: Describe a situation where you had to work with a difficult team member. What was the outcome?
Deliverable: Spoken answers to 2 reported Behavioral Questions 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.
Describe a time when you had to debug a complex issue in your code.
Describe a time when you had to debug a complex issue in your 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?
How do you handle version control in collaborative projects?
How do you handle version control in collaborative projects?
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 faced a significant challenge in a project. How did you handle it?
Tell me about a time you faced a significant challenge in a project. How did you handle 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?
Describe a situation where you had to work with a difficult team member. What was the outcome?
Describe a situation where you had to work with a difficult team member. What was the outcome?
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 prioritize tasks when working on multiple projects simultaneously?
How do you prioritize tasks when working on multiple projects simultaneously?
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 when you had to debug a complex issue in your code.
- 02
How do you handle version control in collaborative projects?
- 03
Tell me about a time you faced a significant challenge in a project. How did you handle it?
- 04
Describe a situation where you had to work with a difficult team member. What was the outcome?
How difficult is the interview process, and how much preparation time is typical?
The interview process is considered rigorous, with candidates often spending several weeks preparing. It is advisable to allocate a few weeks for focused study, particularly on algorithms and system design.
Simon AI Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates typically demonstrate not only strong technical skills but also the ability to communicate effectively and work well within a team. Emotional intelligence and cultural fit are equally important.
Simon AI Software Engineer candidate reports ↗What is the culture and working style at Simon AI?
Simon AI fosters a collaborative and innovative environment. Team members are encouraged to share ideas and support each other in achieving common goals.
Simon AI Software Engineer candidate reports ↗What is the typical timeline from initial screen to offer?
The entire process generally spans 4-6 weeks, depending on scheduling and the number of interview rounds.
Simon AI Software Engineer candidate reports ↗Are there remote work or hybrid expectations?
While many roles can be performed remotely, the specifics may vary by team. It’s important to clarify work arrangements during the interview.
Simon AI Software Engineer candidate reports ↗How many rounds is the Simon AI Software Engineer interview process?
Candidates report 4 stages: Initial Phone Screen, Technical Assessment, Take-Home Assignment, and On-Site Interview. The interview process section above breaks down what each stage covers.
Simon AI Software Engineer candidate reports ↗What topics come up in the Simon AI Software Engineer interview?
Simon AI Software Engineer interviews most often cover Algorithmic Problem Solving, Take-Home Coding Assignments, Coding Interviews (Screen-Share), Data Structures, and Frontend Development, based on topics extracted from real candidate reports.
Simon AI 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.
- 01Simon AI 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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