cswork / libraryOpen practice workspace

Interview guides · McEasy

McEasy Software Engineer Interview Guide

McEasy Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

As a Software Engineer at McEasy, you are at the forefront of transforming the logistics and supply chain industry through advanced technology. McEasy focuses on creating integrated solutions that bridge the gap between physical operations and digital management. Your work directly impacts how businesses track, monitor, and optimize their fleets and assets, making efficiency and reliability the core of your technical contributions. This role is particularly critical given McEasy’s emphasis on IoT (Internet of Things) integration. Whether you are working from our hubs in Surabaya or Jakarta, you will be responsible for building robust systems that handle real-time data from the field. You will find this position highly stimulating if you enjoy solving complex problems that have immediate, tangible effects on operational performance and user experience.

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

Focus areas

  • IoT (Internet of Things)
  • Software Engineering (General)
  • IoT Engineering

The McEasy interview process

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

Initial Assessment

An initial review of your background to gauge your fit for the role.

What to demonstrate

  • An initial review of your background to gauge your fit for the role
  • Depth in IoT (Internet of Things)

How to prepare

  • Answer aloud and timed: Write a function to solve a specific data manipulation problem.
  • Answer aloud and timed: How do you optimize your code for performance?

Hands-on Technical Validation

A coding assessment to evaluate your technical capabilities and problem-solving skills.

What to demonstrate

  • A coding assessment to evaluate your technical capabilities and problem-solving skills
  • Depth in IoT (Internet of Things)

How to prepare

  • Answer aloud and timed: Explain the logic behind your approach to a recent coding challenge.
  • Answer aloud and timed: What are the most important considerations when debugging production code?

Discussion on Problem-Solving

A conversation focused on your approach to problem-solving and long-term fit with the company.

What to demonstrate

  • A conversation focused on your approach to problem-solving and long-term fit with the company
  • Depth in IoT (Internet of Things)

How to prepare

  • Answer aloud and timed: How do you handle edge cases in your implementations?
  • Answer aloud and timed: Walk me through your experience during college or previous roles.

Where candidates lose points

Structure your answers

Use the STAR method (Situation, Task, Action, Result) when discussing past experiences to keep your stories concise and impactful.

Clarify the requirements

If an interview question seems ambiguous, do not hesitate to ask clarifying questions before jumping into a solution.

Focus on the "why

Always explain the reasoning behind your technical choices. This demonstrates depth of knowledge.

Stay calm under pressure

The technical tests are meant to be challenging; stay composed and focus on one step at a time.

Questions & practice

Write a function to solve a specific data manipulation problem.

Medium · Technical Proficiency and Coding

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?

How do you optimize your code for performance?

Medium · Technical Proficiency and Coding

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 logic behind your approach to a recent coding challenge.

Medium · Technical Proficiency and Coding

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?

Stop tag and share joins from fanning out a page

Medium · join fan-out · semi-joins · many-to-many

resource_tag is (resource_id, tag_id) with PK (resource_id, tag_id); resource_share is (resource_id, shared_with_user_id, permission). The tagged-and-shared listing inner-joins resource to both, filters tenant_id, tag_id = ANY($2) and shared_with_user_id = $3, orders by updated_at DESC and takes 50. Pages come back with fewer than 50 distinct resources and the total in the header is far too high. Explain the row multiplication, rewrite both the page query and the count query so each is correct, and name the index each one needs. PostgreSQL 16.

Approach

  1. Do the arithmetic against the predicates that are actually there. An inner join emits one row per matching child row, and both joins are filtered: tag_id = ANY($2) admits only the requested tags, shared_with_user_id = $3 admits one user's share rows. So a resource holding three of the requested tags and shared with $3 once yields three rows, not one — the multiplier is its count of matching tags times its share rows for that single user, and that second factor is 1 unless the table admits duplicate (resource_id, shared_with_user_id) pairs. LIMIT 50 then limits rows rather than resources, and COUNT(*) counts pairs — the header is the product, not the population.
  2. Reject DISTINCT as the fix. It deduplicates after the product has been built, so the planner must materialise and sort the fanned-out set before the LIMIT can apply, and it leaves any SUM or AVG in the same select list wrong.
  3. Rewrite both filters as semi-joins, keeping resource as the only row source: AND EXISTS (SELECT 1 FROM resource_tag rt WHERE rt.resource_id = r.resource_id AND rt.tag_id = ANY($2)) and the same shape against resource_share. A semi-join stops at the first match per resource and preserves the driving index order, so ORDER BY updated_at DESC, resource_id DESC LIMIT 50 still stops after 50 rows.
  4. Count with the same predicates and no join at all: SELECT count(*) FROM resource r WHERE r.tenant_id = $1 AND r.status = 'active' AND EXISTS (...) AND EXISTS (...). Nothing multiplies a resource, so the number is the population.

Follow-up

  • The filter changes from 'any of these tags' to 'all of these tags'. Rewrite it and state what it costs relative to the ANY form.
  • A resource can be shared with the same user twice under different permissions. Does your count change, and should it?

Write the update path that detects a concurrent edit

Medium · optimistic concurrency · transactional outbox · audit history

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

  1. 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.
  2. 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.
  3. 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.
  4. 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?

What was the most challenging technical project you have worked on?

Medium · Experience and Background

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 do you stay updated with new technologies and industry trends?

Medium · Experience and Background

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?

Why are you interested in working with IoT-focused systems?

Medium · Experience and Background

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 would you approach a situation where a system goes down in a production environment?

Medium · Problem-Solving and Logic

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 do you prioritize tasks when faced with multiple urgent technical requirements?

Medium · Problem-Solving and Logic

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 do you communicate technical constraints to non-technical team members?

Medium · Problem-Solving and Logic

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 most important considerations when debugging production code?

Medium · Technical Proficiency and Coding

Approach

  1. Establish what changed and when, before forming any theory.
  2. Pick a bisection that eliminates candidates whichever way it turns out.
  3. Check the instrumentation before believing the symptom.
  4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

  • What would you look at first, and what would it rule out?
  • How would you tell a cause from a coincidence here?

Explain your step-by-step process for troubleshooting a complex software bug.

Medium · Problem-Solving and Logic

Approach

  1. Establish what changed and when, before forming any theory.
  2. Pick a bisection that eliminates candidates whichever way it turns out.
  3. Check the instrumentation before believing the symptom.
  4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

  • What would you look at first, and what would it rule out?
  • How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics McEasy candidates report.

Day 1 — Map the McEasy loop

  • Write out the reported sequence: Initial Assessment, Hands-on Technical Validation, Discussion on Problem-Solving.
  • 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 IoT (Internet of Things)

  • Spend the session on IoT (Internet of Things), which McEasy candidates report being tested on.
  • Write one worked example in IoT (Internet of Things) and time yourself on it.

Deliverable: One timed worked example in IoT (Internet of Things).

Day 3 — Work Software Engineering (General)

  • Spend the session on Software Engineering (General), which McEasy candidates report being tested on.
  • Write one worked example in Software Engineering (General) and time yourself on it.

Deliverable: One timed worked example in Software Engineering (General).

Day 4 — Work IoT Engineering

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

Deliverable: One timed worked example in IoT Engineering.

Day 5 — Answer out loud: Technical Proficiency and Coding

  • Answer aloud, timed: Write a function to solve a specific data manipulation problem.
  • Answer aloud, timed: How do you optimize your code for performance?

Deliverable: Spoken answers to 2 reported Technical Proficiency and Coding question(s), under time.

Day 6 — Answer out loud: Experience and Background

  • Answer aloud, timed: Walk me through your experience during college or previous roles.
  • Answer aloud, timed: What was the most challenging technical project you have worked on?

Deliverable: Spoken answers to 2 reported Experience and Background question(s), under time.

Day 7 — Answer out loud: Problem-Solving and Logic

  • Answer aloud, timed: How would you approach a situation where a system goes down in a production environment?
  • Answer aloud, timed: Explain your step-by-step process for troubleshooting a complex software bug.

Deliverable: Spoken answers to 2 reported Problem-Solving and Logic question(s), under time.

Behavioural preparation

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

How do you handle edge cases in your implementations?

Medium · Technical Proficiency and Coding

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?

Walk me through your experience during college or previous roles.

Medium · Experience and Background

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?

Tell me about a time you had to learn a new language or framework quickly.

Medium · Experience and Background

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?

Describe a time you had to make a technical trade-off.

Medium · Problem-Solving and Logic

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?