Incedo Software Engineer Interview Guide

The 60-second brief

Incedo hires Software Engineers; this guide collects what candidates report about the process.

This guide is scoped to a Software Engineer candidate at Incedo.

Focus areas

• SQL
• Data Structures
• Algorithms (DSA)

The Incedo interview process

Incedo candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Initial Assessment

Automated screening test assessing logical reasoning, quantitative skills, computer science concepts, and code-debugging proficiency.

What to demonstrate

• Automated screening test assessing logical reasoning, quantitative skills, computer science concepts, and code-debugging proficiency
• Depth in SQL

How to prepare

• Answer aloud and timed: What are the core pillars of Object-Oriented Programming, and how does polymorphism differ from inheritance in practice?
• Answer aloud and timed: Explain the concept and application of virtual functions and virtual destructors.

Technical Interview Rounds

Live coding, theoretical concepts, database queries, and project deep-dives based on candidate experience level.

What to demonstrate

• Live coding, theoretical concepts, database queries, and project deep-dives based on candidate experience level
• Depth in SQL

How to prepare

• Answer aloud and timed: What is the difference between static and volatile keywords in C/C++?
• Answer aloud and timed: Explain memory management, dynamic memory allocation, and the risk of memory leaks in long-running processes.

Leadership/HR Discussion

Discussion focused on operational style, cultural alignment, background details, and client engagement readiness.

What to demonstrate

• Discussion focused on operational style, cultural alignment, background details, and client engagement readiness
• Depth in SQL

How to prepare

• Answer aloud and timed: What are Java 8 features (Streams, Lambda expressions) or basic thread execution models?
• Answer aloud and timed: How do you detect a loop in a single linked list? Provide multiple approaches and compare their time/space complexities.

Where candidates lose points

Review your resume thoroughly before your interview

Interviewers at Incedo frequently pull specific questions directly from the skills, tools, and projects you list.

Know Your Fundamentals Cold

Ensure you can comfortably explain Object-Oriented concepts (polymorphism, abstraction, inheritance) with simple code examples or real-world analogies.

Practice Live Query Writing

Practice writing error-free raw SQL joins, aggregations, and subqueries on paper or plain text editors without relying on auto-complete or IDE tools.

Master Automata Fix Debugging

If taking an AMCAT/Mettl screening test, practice identifying logical bugs and syntax errors quickly under strict timed conditions.

Questions & practice

Explain memory management, dynamic memory allocation, and the risk of memory leaks in long-running processes.

Medium · Core Computer Science & OOP Fundamentals

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

What are Java 8 features (Streams, Lambda expressions) or basic thread execution models?

Medium · Core Computer Science & OOP Fundamentals

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

How do you detect a loop in a single linked list? Provide multiple approaches and compare their time/space com

Medium · Data Structures & Algorithms

How do you detect a loop in a single linked list? Provide multiple approaches and compare their time/space complexities.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
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.
4. 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 check if a string or number is a palindrome, or print characters that appear more than onc

Medium · Data Structures & Algorithms

Write a function to check if a string or number is a palindrome, or print characters that appear more than once in a string.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
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.
4. 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?

Explain the difference between linear and non-linear data structures, specifically contrasting a Linked List w

Medium · Data Structures & Algorithms

Explain the difference between linear and non-linear data structures, specifically contrasting a Linked List with a Tree.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
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.
4. 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 basic array manipulation, string reversal, or calculate a factorial iteratively and recursively.

Medium · Data Structures & Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
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.
4. 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?

Explain how a HashMap or Stack operates under the hood, including collision handling or internal push/pop stat

Medium · Data Structures & Algorithms

Explain how a HashMap or Stack operates under the hood, including collision handling or internal push/pop state management.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
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.
4. 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 the difference between DELETE and DROP commands in SQL?

Medium · Database Systems & SQL

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. 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?

Write a query using INNER JOIN, LEFT JOIN, LIMIT, and OFFSET to retrieve specific aggregated records.

Medium · Database Systems & SQL

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. 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?

What are the levels of Database Normalization? How would you structure a multi-entity database in 4NF?

Medium · Database Systems & SQL

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. 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?

What are the core pillars of Object-Oriented Programming, and how does polymorphism differ from inheritance in

Medium · Core Computer Science & OOP Fundamentals

What are the core pillars of Object-Oriented Programming, and how does polymorphism differ from inheritance in practice?

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Explain the concept and application of virtual functions and virtual destructors.

Medium · Core Computer Science & OOP Fundamentals

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. 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 is the difference between static and volatile keywords in C/C++?

Medium · Core Computer Science & OOP Fundamentals

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Explain database integrity constraints and the trade-offs between primary keys and unique keys.

Medium · Database Systems & SQL

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. 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 are the core architectural differences between SQL (relational) and NoSQL database stores?

Medium · Database Systems & SQL

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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 are the key architectural patterns used when building enterprise REST APIs or Microservices?

Medium · Frameworks, Web & Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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?

Describe the lifecycle of an HTTP request from client dispatch to server endpoint and back.

Medium · Frameworks, Web & Architecture

Approach

1. Say who the caller is and what they do when the call fails halfway.
2. Define the identity of a request so a retry cannot double-apply it.
3. Separate accepted, pending, failed and confirmed; they are different facts.
4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

• What happens if the caller retries after a timeout?
• How does a client discover it is on an old version of this contract?

What are SOLID design principles, and how do you apply them to avoid tightly coupled backend services?

Medium · Frameworks, Web & Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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 do you implement robust error handling, unit testing, and input validation in web components?

Medium · Frameworks, Web & Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. 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?

You have 9 balls; 8 have equal weight and 1 is heavier. What is the minimum number of weighings needed to isol

Medium · Logic, Puzzles & Aptitude

You have 9 balls; 8 have equal weight and 1 is heavier. What is the minimum number of weighings needed to isolate the heavier ball?

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

How many times does the digit '8' appear in numbers ranging from 1 to 100? Write pseudo-code to prove your ans

Medium · Logic, Puzzles & Aptitude

How many times does the digit '8' appear in numbers ranging from 1 to 100? Write pseudo-code to prove your answer.

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Solve the classic "fox, chicken, and grain" river crossing riddle step-by-step.

Medium · Logic, Puzzles & Aptitude

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

p99 jumped on one listing filter while p50 stayed flat

Medium · query planning · composite index · percentiles

After a release that added an owner_user_id filter to the resource listing, p99 rose from 90 ms to 1.9 s while p50 stayed at 40 ms. Traffic and row counts are unchanged. resource carries the index (tenant_id, status, updated_at DESC, resource_id DESC). The new query filters tenant_id and owner_user_id, orders by updated_at DESC, resource_id DESC, and takes 20 rows. On PostgreSQL, explain the shape of the regression, prove it from a query plan, and give the index you would add.

Approach

1. Start from the shape. A flat p50 with a moved p99 means a subset of requests changed cost, not all of them, so the first job is naming the subset. Bucket the endpoint's latency by the tenant's row count; the natural hypothesis is that large tenants are a small share of requests and all of the tail.
2. Get the plan for the new query on a large tenant with EXPLAIN (ANALYZE, BUFFERS). Expect an index scan over the tenant's range, a filter discarding most of it, then a Sort feeding the Limit, possibly reporting Sort Method: external merge Disk. Read actual rows on the scan node, not estimated.
3. Explain why the existing index cannot serve it. A composite B-tree is seekable only as a left prefix, and with no equality predicate on status the scan cannot treat updated_at as an ordering, because rows in the tenant's range are ordered by status first. Everything matching must be read and sorted before LIMIT 20 can apply, so a tenant with 400,000 rows pays 400,000 rows to return 20.
4. Add (tenant_id, owner_user_id, updated_at DESC, resource_id DESC). Equality on the first two columns leaves the index ordered by updated_at within that pair, so the plan becomes an index scan that stops after 20 rows with no Sort node. PostgreSQL can scan a B-tree backwards, so the DESC markers matter only if the two sort columns ever disagree in direction; keeping them explicit documents the order the keyset cursor depends on.

Follow-up

• The endpoint paginates with OFFSET. What does page 500 cost with your index, and what does the keyset version cost?
• How would you have caught this before release, given that a 10,000-row seed database produces the same plan shape at an unnoticeable cost?

Suggested practice checklist

Built from the rounds and topics Incedo candidates report.

Day 1 — Map the Incedo loop

• Write out the reported sequence: Initial Assessment, Technical Interview Rounds, Leadership/HR Discussion.
• 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.

Day 2 — Work SQL

• Spend the session on SQL, which Incedo candidates report being tested on.
• Write one worked example in SQL and time yourself on it.

Deliverable: One timed worked example in SQL.

Day 3 — Work Data Structures

• Spend the session on Data Structures, which Incedo candidates report being tested on.
• Write one worked example in Data Structures and time yourself on it.

Deliverable: One timed worked example in Data Structures.

Day 4 — Work Algorithms (DSA)

• Spend the session on Algorithms (DSA), which Incedo candidates report being tested on.
• Write one worked example in Algorithms (DSA) and time yourself on it.

Deliverable: One timed worked example in Algorithms (DSA).

Day 5 — Answer out loud: Core Computer Science & OOP Fundamentals

• Answer aloud, timed: What are the core pillars of Object-Oriented Programming, and how does polymorphism differ from inheritance in practice?
• Answer aloud, timed: Explain the concept and application of virtual functions and virtual destructors.

Deliverable: Spoken answers to 2 reported Core Computer Science & OOP Fundamentals question(s), under time.

Day 6 — Answer out loud: Data Structures & Algorithms

• Answer aloud, timed: How do you detect a loop in a single linked list? Provide multiple approaches and compare their time/space complexities.
• Answer aloud, timed: Write a function to check if a string or number is a palindrome, or print characters that appear more than once in a string.

Deliverable: Spoken answers to 2 reported Data Structures & Algorithms question(s), under time.

Day 7 — Answer out loud: Database Systems & SQL

• Answer aloud, timed: What is the difference between DELETE and DROP commands in SQL?
• Answer aloud, timed: Write a query using INNER JOIN, LEFT JOIN, LIMIT, and OFFSET to retrieve specific aggregated records.

Deliverable: Spoken answers to 2 reported Database Systems & SQL question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

How do components communicate in React or Angular, and how do you handle asynchronous state management?

Medium · Frameworks, Web & Architecture

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. 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?

Narrate an outage you owned from page to postmortem

Hard · incident response · blast radius · postmortems

Pick an incident you personally drove, ideally one where writes were affected rather than reads. In six to eight minutes: state the symptom as it first appeared on a dashboard, the blast radius you established before you knew the cause, the mitigation you applied and when, the mechanism you eventually proved, and the follow-up that would prevent a repeat. Bring numbers: error rate, tenants affected, minutes to mitigate, minutes to resolve. If you cannot name what you measured, choose a different incident.

Approach

1. Open on the signal rather than the cause: which metric at which percentile moved, on which service, at what time, so the listener follows the same evidence you had rather than a conclusion you already reached.
2. Separate mitigation from diagnosis out loud. State what you did to stop the bleeding (flag off, shed traffic, drain a lease, roll back a deploy) and say plainly that you did it before the mechanism was known, because those are two jobs with different deadlines.
3. Establish blast radius in countable terms: how many tenants, how many writes, and crucially whether the effect was loss or only delay. An append-only revision table or a pending outbox row means the change survived and the projection was merely behind, which is a repair rather than a data-loss incident.
4. Prove the mechanism instead of asserting it. Name the trace span that grew, the plan that flipped to a sequential scan, the lease that expired, plus one alternative you ruled out and the signal that stayed flat while you ruled it out.

Follow-up

• What would you do differently in the first five minutes, given the same dashboard and no more information?
• Which follow-up action did you deliberately not take, and why was dropping it the right call?

Unblock an engineer without taking the keyboard

Easy · mentoring · leases · at-least-once

A teammate has spent two days on a job handler that occasionally writes duplicate rows. They are certain the queue is delivering twice by mistake. You suspect a lease expiring under a slow handler, so the job is running concurrently with itself. Describe how you have unblocked someone in this position: what you asked before offering a hypothesis, what you showed them rather than told them, and what you left them owning. Then say what you would do if their theory turned out to be the right one.

Approach

1. Ask before diagnosing, and ask for things answerable from data they already have: the attempt count on the job rows that produced duplicates, the handler's observed duration against its lease expiry, and whether the duplicate rows share a natural key that a unique constraint could have caught.
2. Teach the shape rather than the answer. A lease cannot distinguish a dead worker from a slow one, so a handler that outruns its lease is running twice by design, and deploys deliver the other half by killing handlers mid-run on every rollout. Both of their candidate theories produce identical duplicate rows, which is why the evidence has to come from timings rather than from argument.
3. Hand over a checklist they execute: a natural key on every write the handler performs so the second copy collides rather than appends, the record of intent written before any external effect, a lease heartbeat while running, and the metric that shows it working.
4. Keep ownership with them deliberately. Pair on the first write, then step back; if you finish it yourself you have closed one ticket and left the same person stuck on the next redelivery.

Follow-up

• How would you distinguish a genuine double-delivery from a lease expiry using only the data already stored?
• Their handler calls an external endpoint before recording that it did. What do you tell them to change first?