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Daymon Software Engineer Interview Guide

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

The 60-second brief

A Software Engineer at Daymon plays a crucial role in driving innovation and efficiency in the development of software solutions that enhance the company's core business operations. This position is integral to the development of products that not only meet the needs of clients but also set the standard for quality and performance in the retail and consumer goods sector. You will be working on sophisticated projects that require both technical expertise and a strong understanding of user needs, ensuring that the software developed is robust, scalable, and user-friendly. The impact of this role extends beyond coding; as a Software Engineer, you will collaborate with cross-functional teams, including product managers and designers, to define technical requirements, troubleshoot issues, and implement enhancements.

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

Focus areas

  • Technical Interview Communication
  • Stakeholder Communication
  • Technical Depth Assessment

The Daymon interview process

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

Initial Communication

HR department contacts you to schedule your interview.

What to demonstrate

  • HR department contacts you to schedule your interview
  • Depth in Technical Interview Communication

How to prepare

  • Answer aloud and timed: What programming languages are you proficient in, and how have you used them in past projects?
  • Answer aloud and timed: Explain a challenging technical problem you faced and how you resolved it.

Phone Interview

Discuss your background and technical skills with a hiring manager or senior engineer.

What to demonstrate

  • Discuss your background and technical skills with a hiring manager or senior engineer
  • Depth in Technical Interview Communication

How to prepare

  • Answer aloud and timed: Describe your experience with version control systems, particularly Git.
  • Answer aloud and timed: How do you ensure code quality and maintainability in your projects?

Additional Interviews

Participate in further interviews focusing on technical capabilities and cultural fit.

What to demonstrate

  • Participate in further interviews focusing on technical capabilities and cultural fit
  • Depth in Technical Interview Communication

How to prepare

  • Answer aloud and timed: What are your strategies for debugging and testing your code?
  • Answer aloud and timed: Can you walk us through the design of a system you have built, highlighting key architectural decisions?

Where candidates lose points

Practice coding regularly

Engaging with coding challenges on platforms like LeetCode or HackerRank will sharpen your skills and problem-solving ability.

Understand the company’s products

Familiarize yourself with Daymon's offerings and how your role as a Software Engineer contributes to their success in the market.

Be prepared for behavioral questions

Reflect on your past experiences and how they relate to the role. Use the STAR method (Situation, Task, Action, Result) to structure your answers.

Demonstrate teamwork in your responses

Highlight instances where you successfully collaborated with others, as this aligns with Daymon's emphasis on a collaborative work environment.

Questions & practice

Write a function to reverse a linked list. Explain your thought process as you code.

Medium · Coding / 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?

How would you find the longest substring without repeating characters?

Medium · Coding / 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?

Discuss the time and space complexity of your solution.

Medium · Coding / 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?

Keep soft-deleted accounts from blocking re-registration

Easy · soft delete · unique constraints · engine differences

app_user holds user_id, tenant_id, email CITEXT, password_hash (NULL for SSO principals), email_verified_at, auth_version, status ('invited','active','suspended','deactivated'), created_at, updated_at, deleted_at. Two live accounts for one address inside a tenant must be impossible, but an address freed by a soft delete must be reusable, and the same tenant may delete and re-register it repeatedly. Write the uniqueness DDL for PostgreSQL 16, then the equivalent for MySQL 8 where partial indexes do not exist, and say what each permits once three deleted rows already hold that address.

Approach

  1. Start from what is actually unique: not (tenant_id, email), but (tenant_id, email) among live rows. PostgreSQL says that directly — CREATE UNIQUE INDEX app_user_live_email ON app_user (tenant_id, email) WHERE deleted_at IS NULL. A full constraint over the same two columns burns the address permanently the first time someone deletes an account.
  2. Keep case-insensitivity in the type or the index, never in the application: CITEXT as given, or UNIQUE (tenant_id, lower(email)) as an expression index where the extension is unavailable. A case-sensitive unique column is exactly how two accounts for one human appear.
  3. For MySQL 8 the predicate has to move inside the key: add a discriminator column that is a constant 0 while the row is live and is set to user_id on delete, with UNIQUE (tenant_id, email, deleted_marker). Live rows share the constant and still collide; deleted rows differ from each other and stop colliding.
  4. State the NULL variant and its dependency: leaving the marker NULL for deleted rows also works, because a unique index treats NULLs as distinct — true in MySQL, and true in PostgreSQL only under the default NULLS DISTINCT, which PostgreSQL 15 lets you reverse. Check the polarity against the three existing deleted rows: constant-on-live is what preserves the collision you want, and reversing it silently admits duplicate live accounts.

Follow-up

  • A deleted account re-registers with the same address the next day. Do the old resource rows follow the new user_id, and how does the API keep the two principals apart?
  • How do you honour an erasure request while resource_revision.actor_user_id still references this table?

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?

What programming languages are you proficient in, and how have you used them in past projects?

Medium · Technical / Domain Questions

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 a challenging technical problem you faced and how you resolved it.

Medium · Technical / Domain Questions

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 ensure code quality and maintainability in your projects?

Medium · Technical / Domain Questions

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?

Can you walk us through the design of a system you have built, highlighting key architectural decisions?

Medium · System Design / 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 would you approach designing a system that needs to handle millions of users?

Medium · System Design / 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?

Discuss how you would balance performance and scalability in your designs.

Medium · System Design / 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?

What design patterns do you frequently use, and why?

Medium · System Design / 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 would you approach resolving a system outage in a production environment?

Medium · Problem-Solving / Case Studies

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?

If given a new technology to implement, how would you go about learning and applying it?

Medium · Problem-Solving / Case Studies

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 your strategies for debugging and testing your code?

Medium · Technical / Domain Questions

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 Daymon candidates report.

Day 1 — Map the Daymon loop

  • Write out the reported sequence: Initial Communication, Phone Interview, Additional Interviews.
  • 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 Technical Interview Communication

  • Spend the session on Technical Interview Communication, which Daymon candidates report being tested on.
  • Write one worked example in Technical Interview Communication and time yourself on it.

Deliverable: One timed worked example in Technical Interview Communication.

Day 3 — Work Stakeholder Communication

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

Deliverable: One timed worked example in Stakeholder Communication.

Day 4 — Work Technical Depth Assessment

  • Spend the session on Technical Depth Assessment, which Daymon candidates report being tested on.
  • Write one worked example in Technical Depth Assessment and time yourself on it.

Deliverable: One timed worked example in Technical Depth Assessment.

Day 5 — Answer out loud: Technical / Domain Questions

  • Answer aloud, timed: What programming languages are you proficient in, and how have you used them in past projects?
  • Answer aloud, timed: Explain a challenging technical problem you faced and how you resolved it.

Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.

Day 6 — Answer out loud: System Design / Architecture

  • Answer aloud, timed: Can you walk us through the design of a system you have built, highlighting key architectural decisions?
  • Answer aloud, timed: How would you approach designing a system that needs to handle millions of users?

Deliverable: Spoken answers to 2 reported System Design / Architecture question(s), under time.

Day 7 — Answer out loud: Behavioral / Leadership

  • Answer aloud, timed: Describe a time when you had to work with a difficult team member. How did you handle it?
  • Answer aloud, timed: What do you consider your biggest professional achievement?

Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.

Behavioural preparation

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

Describe your experience with version control systems, particularly Git.

Medium · Technical / Domain Questions

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 when you had to work with a difficult team member. How did you handle it?

Medium · Behavioral / Leadership

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?

What do you consider your biggest professional achievement?

Medium · Behavioral / Leadership

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?

How do you prioritize tasks when working on multiple projects?

Medium · Behavioral / Leadership

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 us about a time when you received constructive criticism. How did you respond?

Medium · Behavioral / Leadership

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 when you had to make a decision with incomplete information.

Medium · Problem-Solving / Case Studies

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?