As a Software Engineer at DEPT, you operate at the intersection of creativity, technology, and data to build cutting-edge digital experiences for global brands. This role is vital to the agency's mission of accelerating digital growth and transformation for clients across diverse industries. You will be responsible for translating complex architectural visions and design mockups into high-performing, scalable, and accessible software solutions that engage millions of users. What makes this position both critical and challenging is the agency environment, where you must balance rapid delivery timelines with uncompromising code quality. You will frequently collaborate with cross-functional teams comprising Product Managers, UI/UX Designers, and Quality Assurance Engineers, as well as communicate directly with external clients. Whether you are optimizing a high-traffic e-commerce platform, implementing advanced React state management, or refining accessibility standards, your work directly impacts the digital presence of enterprise-level partners. Expect a dynamic, fast-paced atmosphere where continuous learning and adaptability are paramount. While the technology stack often centers on modern frontend and backend frameworks, the core of the role relies on your ability to solve unstructured problems collaboratively. Success at DEPT requires not just technical prowess, but also a consultative mindset and a genuine passion for digital craftsmanship.
Recruiter Screening
reportedInitial introductory screening with a recruiter to align on background, motivations, and cultural fit.
What to demonstrate
- Initial introductory screening with a recruiter to align on background, motivations, and cultural fit
- Depth in React
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
reportedCandidates complete a practical take-home coding assignment or participate in a live technical discussion.
What to demonstrate
- Candidates complete a practical take-home coding assignment or participate in a live technical discussion
- Depth in React
How to prepare
- Answer aloud and timed: When implementing a landing page from a Figma design, what is your workflow for ensuring pixel-perfection and responsive layout?
- Answer aloud and timed: Can you explain how you utilize advanced ARIA labels and accessibility best practices in your components?
Deep-Dive Conversations
reportedFinal discussions with engineering leads and team members to review technical solutions and interpersonal dynamics.
What to demonstrate
- Final discussions with engineering leads and team members to review technical solutions and interpersonal dynamics
- Depth in React
How to prepare
- Answer aloud and timed: How do you optimize bundle size and rendering performance in a heavy web application?
- Answer aloud and timed: How would you structure a scalable frontend architecture for a multi-tenant client application?
PracHub editorial advice for the preparation topics above.
Adopt a consultative mindset
Remember that DEPT is a digital agency. Frame your technical solutions around business value, user experience, and client objectives rather than just writing code in isolation.
Over-communicate during take-home assignments
Include a clear README.md in your project submissions explaining your architectural decisions, setup instructions, and any trade-offs or future improvements you would make.
Prepare STAR-format behavioral stories
Be ready to discuss past projects where you handled tight deadlines, resolved disagreements with designers, or managed unexpected technical roadblocks.
Brush up on design-to-code workflows
Since design implementation is a frequent evaluation point, practice translating mockups into pixel-perfect, responsive components swiftly and accurately.
Ask insightful questions about the team
Use the time allotted for candidate questions to inquire about tech stacks, project handoff processes, and cross-functional collaboration dynamics within the specific engineering squad.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Can you explain how you handle asynchronous data fetching, caching, and error boundaries?
Can you explain how you handle asynchronous data fetching, caching, and error boundaries?
Approach
- Say what the runtime actually does before reasoning about the code.
- Name what is shared across threads and what owns each piece of state.
- Identify the window where an invariant is briefly untrue.
- 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?
Collapse a redelivered event batch into per-aggregate high-water marks
You drain a batch of up to 5,000,000 events, each (aggregate_id BIGINT, aggregate_version INT, event_type, payload). The log guarantees order within one aggregate only; the batch merges 64 partitions, and a relay failover has redelivered a range, so an older version for an aggregate can appear after a newer one. Given a map of last_applied_version per aggregate, produce the events worth applying, at most one per (aggregate_id, version), plus the count discarded. Target O(n) time. State the memory for 2,000,000 distinct aggregates and what you do when it does not fit.
Approach
- One pass, one hash map from aggregate_id to the highest version kept, and a discard counter. An event whose version is at or below last_applied_version for its aggregate is dropped without further work, which is the whole reason the event carries its version rather than a delta. O(n) expected time, O(d) space in distinct aggregates.
- Keep the maximum, never the last occurrence. The redelivered range means the final appearance of an aggregate in the batch can be an older version than one seen earlier in the same batch, so last-wins applies stale state over newer state and the projection regresses with no error anywhere.
- Cost the memory instead of calling it large: an 8-byte key plus a 4-byte version is 12 bytes of payload, and an open-addressed table held at a 0.7 load factor costs roughly 17 bytes per entry before per-slot metadata, so 2,000,000 aggregates is tens of megabytes in a native layout and several times that in a runtime that boxes both key and value.
- If the distinct set exceeds memory, partition on hash(aggregate_id) mod P and reduce each partition independently. Every event for one aggregate hashes to the same partition, so the per-partition result is exact and the merge is concatenation rather than a second reduction.
Follow-up
- The payload is a patch rather than a snapshot, so applying only the highest version loses the intermediate changes. What changes in your reduction?
- How do you detect that version 7 arrived while version 6 was never delivered, and what should the consumer do about the gap?
Track a rolling failure rate per destination for circuit decisions
The egress service delivers about 1,500 webhooks per second across roughly 40,000 destinations, each call bounded by a 10 second timeout. Maintain, per destination, the failure rate over the trailing 60 seconds so a caller can ask before dispatch whether the circuit should open. Attempts arrive as (destination_id, finished_at_ms, outcome). Requirement: amortised O(1) per attempt, with total memory bounded by the destination count rather than by traffic. Give the structure, its exact memory, and the rule that stops a destination with three attempts from opening a circuit.
Approach
- Name the exact-deque version and then reject it as the default. Holding timestamps and advancing a tail pointer past anything older than now minus 60 seconds is a correct two-pointer window at amortised O(1) per attempt, but its memory tracks in-window traffic, so one destination in a retry storm holds hundreds of thousands of entries while thousands of quiet destinations hold none.
- Use a ring of 60 one-second buckets per destination, each bucket a pair of counters for attempts and failures. On an attempt, advance the ring by the elapsed whole seconds, zeroing at most min(elapsed, 60) buckets, then increment the head. That is amortised O(1) with a fixed footprint per destination.
- State the footprint: 60 buckets times two 4-byte counters is 480 bytes of payload per destination, so 40,000 destinations is roughly 20 to 25 MB with per-entry overhead, bounded by the catalogue rather than by the rate. The cost is granularity, since the oldest bucket ages out in whole seconds, which is far tighter than the decision needs.
- Require a minimum sample before the circuit may open. A destination with three attempts and three failures reads as 100 percent and is not evidence; a floor of roughly 20 attempts in the window makes the ratio meaningful, and below that floor use a run of consecutive failures as the trigger instead.
Follow-up
- The fleet is 30 instances and each sees roughly a thirtieth of a destination's traffic. Where does the rate actually live, and what does a per-instance answer get wrong?
- A destination answers in 9.5 seconds and succeeds. It is not failing but it is consuming your per-destination concurrency. What signal should open the circuit here?
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?
Replace offset paging on the resource feed with keyset
resource holds resource_id, tenant_id, owner_user_id, title, body_ref, version, status ('draft','active','archived','deleted'), created_at, updated_at, deleted_at, with an index on (tenant_id, status, updated_at DESC, resource_id DESC). The listing endpoint returns active resources for one tenant, newest update first, 50 per page, today with LIMIT 50 OFFSET n. Tenants reach page 400 and rows are created while they read. Write the keyset query, define what the cursor carries and how it is encoded, and say which part of the index each predicate uses. Assume PostgreSQL 16.
Approach
- Name the two failures separately. OFFSET 20000 makes the server produce and discard 20,000 rows, so page cost grows with depth rather than with page size. Independently, any write that changes how many rows sort above the offset moves the window between two fetches, and the direction decides which anomaly you get: an insert lands at the head of updated_at DESC and pushes already-returned rows down past the boundary, so they are returned a second time; a delete above the offset, or a row whose updated_at is bumped above the cursor, pulls rows up and one is never returned at all. Nothing in the response reveals either.
- Write the seek: WHERE tenant_id = $1 AND status = 'active' AND (updated_at, resource_id) < ($2, $3) ORDER BY updated_at DESC, resource_id DESC LIMIT 50. The row-value comparison is one index range rather than a disjunction, and both columns are NOT NULL, which is what makes that comparison well defined.
- Map each predicate onto the index: tenant_id and status are equality on the leading columns, (updated_at, resource_id) is the range, and the ORDER BY matches the index order so no Sort node appears and the scan stops after 50 rows. The DESC in the definition only matters for mixed directions — a plain ascending btree on the same columns is read backwards for this query.
- Put both sort columns in the cursor and nothing the client can tamper with into another tenant: base64 of (updated_at, resource_id), validated server-side, with tenant_id taken from the principal.
Follow-up
- The client asks for 'jump to page 400'. What do you offer instead, and what does the honest version cost?
- Sort order becomes user-selectable across four columns. How many indexes is that, and which would you refuse to add?
How do you approach state management in complex component trees?
How do you approach state management in complex component trees?
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?
When implementing a landing page from a Figma design, what is your workflow for ensuring pixel-perfection and
When implementing a landing page from a Figma design, what is your workflow for ensuring pixel-perfection and responsive layout?
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?
Can you explain how you utilize advanced ARIA labels and accessibility best practices in your components?
Can you explain how you utilize advanced ARIA labels and accessibility best practices in your components?
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?
How do you optimize bundle size and rendering performance in a heavy web application?
How do you optimize bundle size and rendering performance in a heavy web application?
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?
How would you structure a scalable frontend architecture for a multi-tenant client application?
How would you structure a scalable frontend architecture for a multi-tenant client 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 strategies do you use for component reusability and design system integration?
What strategies do you use for component reusability and design system integration?
Approach
- Say who the caller is and what they do when the call fails halfway.
- Define the identity of a request so a retry cannot double-apply it.
- Separate accepted, pending, failed and confirmed; they are different facts.
- 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?
How do you approach writing clean, maintainable code that can be easily handed off to other team members?
How do you approach writing clean, maintainable code that can be easily handed off to other team members?
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 do you prioritize tasks when juggling multiple client projects simultaneously?
How do you prioritize tasks when juggling multiple client projects simultaneously?
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 is your process for testing your code before submitting it for review?
What is your process for testing your code before submitting it for review?
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?
How do you approach debugging a performance bottleneck reported by a client?
How do you approach debugging a performance bottleneck reported by a client?
Approach
- Establish what changed and when, before forming any theory.
- Pick a bisection that eliminates candidates whichever way it turns out.
- Check the instrumentation before believing the symptom.
- 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?
Can you review this provided code snippet, identify potential memory leaks or anti-patterns, and suggest impro
Can you review this provided code snippet, identify potential memory leaks or anti-patterns, and suggest improvements?
Approach
- Establish what changed and when, before forming any theory.
- Pick a bisection that eliminates candidates whichever way it turns out.
- Check the instrumentation before believing the symptom.
- 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?
Built from the rounds and topics DEPT candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the DEPT loop
- Write out the reported sequence: Recruiter Screening, Technical Evaluation, Deep-Dive Conversations.
- 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 React
- Spend the session on React, which DEPT candidates report being tested on.
- Write one worked example in React and time yourself on it.
Deliverable: One timed worked example in React.
03Work Home Assignments
- Spend the session on Home Assignments, which DEPT candidates report being tested on.
- Write one worked example in Home Assignments and time yourself on it.
Deliverable: One timed worked example in Home Assignments.
04Work JavaScript
- Spend the session on JavaScript, which DEPT candidates report being tested on.
- Write one worked example in JavaScript and time yourself on it.
Deliverable: One timed worked example in JavaScript.
05Answer out loud: Frontend & Core Technologies
- Answer aloud, timed: Can you walk me through your experience building and scaling applications with React and modern JavaScript?
- Answer aloud, timed: How do you approach state management in complex component trees?
Deliverable: Spoken answers to 2 reported Frontend & Core Technologies question(s), under time.
06Answer out loud: Technical Case & Architecture
- Answer aloud, timed: How would you structure a scalable frontend architecture for a multi-tenant client application?
- Answer aloud, timed: Can you explain how you handle asynchronous data fetching, caching, and error boundaries?
Deliverable: Spoken answers to 2 reported Technical Case & Architecture question(s), under time.
07Answer out loud: Behavioral & Cultural Fit
- Answer aloud, timed: Why do you want to work at DEPT as a Software Engineer?
- Answer aloud, timed: How do you handle tight project deadlines without sacrificing code quality?
Deliverable: Spoken answers to 2 reported Behavioral & Cultural Fit 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.
Can you walk me through your experience building and scaling applications with React and modern JavaScript?
Can you walk me through your experience building and scaling applications with React and modern JavaScript?
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?
Can you discuss a time when you had to refactor legacy code to improve maintainability and performance?
Can you discuss a time when you had to refactor legacy code to improve maintainability and performance?
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?
Why do you want to work at DEPT as a Software Engineer?
Why do you want to work at DEPT as a Software Engineer?
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 tight project deadlines without sacrificing code quality?
How do you handle tight project deadlines without sacrificing code quality?
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?
Can you describe a situation where you disagreed with a design or product decision, and how you resolved it?
Can you describe a situation where you disagreed with a design or product decision, and how you resolved 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?
How do you manage client expectations when technical roadblocks arise during development?
How do you manage client expectations when technical roadblocks arise during development?
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 mentor a junior developer or onboard a teammate to a new codebase.
Tell me about a time you had to mentor a junior developer or onboard a teammate to a new codebase.
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 feedback during a technical code review from senior peers?
How do you handle feedback during a technical code review from senior peers?
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
Can you walk me through your experience building and scaling applications with React and modern JavaScript?
- 02
Can you discuss a time when you had to refactor legacy code to improve maintainability and performance?
- 03
Why do you want to work at DEPT as a Software Engineer?
- 04
How do you handle tight project deadlines without sacrificing code quality?
How difficult is the interview process, and how much preparation time should I plan for?
The interview process is moderately rigorous, focusing heavily on practical engineering skills rather than trick questions. Plan for at least two weeks of targeted preparation, reviewing core framework mechanics, practicing take-home project architectures, and brushing up on behavioral narratives.
DEPT Software Engineer candidate reports ↗What differentiates successful candidates from those who do not pass?
Successful candidates distinguish themselves through clear communication, attention to detail in their coding assignments, and a collaborative attitude. They don't just write working code; they explain their architectural trade-offs, ask thoughtful questions, and demonstrate genuine interest in client success.
DEPT Software Engineer candidate reports ↗What is the culture like at DEPT for software engineers?
The engineering culture is fast-paced, highly collaborative, and client-focused. Teams operate with a high degree of autonomy while supporting each other across diverse digital projects, encouraging continuous learning and knowledge sharing.
DEPT Software Engineer candidate reports ↗How long does the entire hiring process take from application to offer?
On average, the process spans about two to four weeks. Timelines can vary based on scheduling availability for technical interviews and home assignment reviews, but recruiters typically maintain active communication throughout the pipeline.
DEPT Software Engineer candidate reports ↗Are there opportunities for remote work or hybrid flexibility?
Work arrangements depend on the specific regional office and client requirements, with many teams offering hybrid or flexible remote models. Be sure to discuss location and working model expectations during your initial recruiter screen.
DEPT Software Engineer candidate reports ↗What topics does DEPT test in interviews?
DEPT interviews most often cover Presentation Skills, Communication Skills, Stakeholder Management, Problem Solving, and React. The exact emphasis depends on the specific role you apply for.
DEPT 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.
- 01DEPT 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
Explore related engineering environments and compare the preparation focus.
Vercel Software Engineer Interview Guide
Debugging practice for Vercel software engineer prep built on a reproduction you trust, narrowing to the smallest failing input, and changing one variable per run so the result stays attributable.
Spotify Software Engineer Interview Guide
Timed practice for Spotify software engineer candidates who lose time to the clock: short problems taken end to end, then reviewed against a written rubric rather than a passing test run.
Shopify Software Engineer Interview Guide
Timed practice for Shopify software engineer candidates who lose time to the clock: short problems taken end to end, then reviewed against a written rubric rather than a passing test run.
Ramp Software Engineer Interview Guide
Systems practice for Ramp software engineer candidates, weighted toward payments and lending work: the load that actually arrives, the failure modes that matter there, and the invariants a partial outage must not break.