AvalonBay Communities Software Engineer Interview Guide

The 60-second brief

AvalonBay Communities is a real estate company, and the engineering work candidates describe is software used by two groups: residents and property managers. The role description candidates cite names project areas across property management systems, resident-facing applications and data analytics platforms. The day-to-day work covers the whole lifecycle: gathering requirements, design, code review, deployment and maintenance, alongside product managers, UX/UI designers and other engineers. For your preparation, that means your examples should show business applications with real users and real data (records, transactions, workflows that cross systems), not only isolated algorithm work.

This guide is for engineers interviewing for the Software Engineer role at AvalonBay Communities. The requirements candidates describe ask for Java, Python or C#, experience with software development methodologies, API design and database management, and typically 2-5 years of experience. Web frameworks, AWS or Azure, DevOps practices and data analytics tools are listed as a plus. The guide covers both reported stages, question-specific guidance for all 25 reported questions (coding fundamentals, system design, engineering practice and behavioral), the mistakes that cost points on those question types, and a seven-day plan.

Candidates report two stages, a Phone Screening and then Interviews with Management, over roughly 2-4 weeks. The later conversations are described as centring on past experience and future goals, and the process overall mixes technical, behavioral and problem-solving questions.

Focus areas

• Communication Skills
• Soft Skills for Engineering Roles
• Past Experience Articulation

Overview

The work candidates describe is business software for residents and property managers: modelling units, leases, payments and requests, exposing them through APIs, and keeping data consistent when several systems touch the same record. That is why the reported design questions (a property management application, database schema considerations, high traffic, microservices, integration and data consistency) are the centre of the technical preparation. Practise them with this domain in mind: a lease that must not overlap another on the same unit, a payment that must not be recorded twice, a maintenance request that moves through states.

The reported questions fall into five groups. Technical and domain questions ask about your languages, cloud experience and how you keep code maintainable. Problem-solving cases cover debugging, improving a legacy system, gathering requirements from stakeholders, and testing new features. The coding questions are fundamentals: reversing a linked list, the longest common prefix of an array of strings, DFS versus BFS, hash tables, and a sorting algorithm with its complexity. These reward a correct, cleanly written solution in Java, Python or C# with the complexity stated and the empty and single-element cases handled, more than any advanced trick.

The topics candidates report being tested on are communication skills, soft skills for engineering roles, past experience articulation, behavioral interviewing and future goals articulation, and the second stage is described as interviews with managers and project stakeholders. A large share of your preparation is therefore a story bank: six to eight concrete stories with your own actions and measured results, each mapped to several of the reported prompts, plus a specific answer about where you want your career to go. Candidates also list Agile methodology, testing frameworks and Git among the areas discussed, so have one example of each from your own work ready to cite.

The AvalonBay Communities interview process

These are the two stages candidates report. Candidates do not say which stage carries the coding and design questions, so prepare those for the whole process rather than for one conversation.

Phone Screening

Candidates describe the Phone Screening as an early check of their background and why they want this role. Treat it as the place where your fit with the reported requirements is established: one primary language from Java, Python or C#, the APIs and databases you have built and run, and any AWS or Azure work. Have a short walkthrough of your experience that ends on why property management and resident-facing software interests you, answers ready for the languages and cloud questions, and your own questions about the team, the project area (property management systems, resident applications or data analytics) and the rest of the process, including hybrid arrangements, which candidates report depend on the team.

What to demonstrate

• How your background lines up with the reported requirements: Java, Python or C#, API design and database management
• Your reasons for wanting this role
• Clear, concise communication about your own experience

How to prepare

• A walkthrough of your experience that names your primary language, one API you designed and one database you modelled or maintained, ending on why this role.
• Spoken answers to the languages question and the cloud services question, each anchored in one project with specific services, frameworks and outcomes.
• Three questions to ask: which project area the team works on, what the later interviews involve, and how hybrid work is set up for the team.

Interviews with Management

Candidates report that the later conversations can involve senior managers and project stakeholders, and that they centre on past experience and future goals. Across the process, candidates describe technical questions, behavioral prompts and problem-solving discussion, with collaboration and the resident experience as recurring themes. Approach it as a set of conversations with people who may not all be engineers: tell each story with your own decisions and a measured result, explain technical choices in terms of what they changed for users or the business, and be ready to discuss design and engineering practice at the depth a technical manager would follow. Have a clear answer about the next stage of your career and how this role fits it.

What to demonstrate

• Articulating past projects: your role, decisions and measured results
• Future goals and how this role fits them
• Collaboration with cross-functional colleagues and non-technical stakeholders
• Technical judgment as shown through your past work

How to prepare

• A story bank of six to eight STAR stories mapped to the reported behavioral prompts (difficult team member, initiative, tight deadlines, a project you led, a decision with limited information).
• A two-level explanation of one system you built: a short version for a non-technical stakeholder and a deeper one covering schema, APIs and trade-offs.
• An answer on future goals that names the skills you want to build and connects them to property management, resident or data analytics work.
• Spoken answers to the code quality, debugging, legacy system and requirements-gathering questions, each with a real example.

Where candidates lose points

Answering the languages or cloud question with a list of every technology on your CV and no project behind any of them.

Lead with one primary language from Java, Python or C# and one cloud setup on AWS or Azure, each tied to a project, the specific frameworks or services, and a result. Name secondary skills briefly and say honestly how deep they go.

Designing the property management application by jumping straight to microservices, Kubernetes and caching before naming a single entity or workflow.

Start with the users (residents, property managers, maintenance staff), the entities (unit, lease, payment, maintenance request) and the constraints that matter (no overlapping leases, no double-charged payments). Begin with a modular monolith on a relational database and say which piece you would split out later and why.

Telling behavioral stories in 'we' with no clear personal action and no result, which leaves nothing to discuss in the management conversations.

Write six to eight STAR stories in the first person, each with a number in the result (time saved, errors cut, adoption). Map each story to two or three of the reported prompts so you can reuse it without sounding scripted, and prepare a specific answer on your future goals.

Fumbling the fundamentals coding questions: losing the next pointer when reversing a linked list, or crashing on an empty array in the longest common prefix.

Write each reported coding question in your primary language from a blank file, then trace it on the empty, single-element and normal cases before declaring it done. State time and space complexity unprompted, and for sorting know which algorithm your language's library uses.

Answering engineering-practice questions (code quality, testing, debugging, legacy systems) with principles only and no example from your own work.

For each of those questions, pair the method with one real case: the bug you bisected, the untested module you wrapped in characterisation tests, the feature you released behind a flag. Mention the Agile, testing-framework and Git practices you actually used, by name.

Questions & practice

Write a function to reverse a linked list.

Medium · Coding / Algorithms

Approach

1. Iterative solution: keep prev = null and curr = head; in a loop save next = curr.next, set curr.next = prev, move prev = curr and curr = next; return prev as the new head.
2. Complexity: O(n) time, O(1) extra space. The recursive version (reverse the rest, then head.next.next = head and head.next = null) is also O(n) time but uses O(n) stack and can overflow on long lists.
3. Edge cases: empty list returns null, a single node returns itself; saving next before overwriting the pointer is the step that is easy to get wrong.
4. Trace it aloud on 1 -> 2 -> 3 to show the pointers at each step, and write it in your primary language with a small node class.

Follow-up

• Reverse only the nodes between positions m and n.
• Reverse the list in groups of k nodes.
• How does the code change for a doubly linked list?

How would you find the longest common prefix among an array of strings?

Medium · Coding / Algorithms

Approach

1. Vertical scanning: for each index i of the first string, check that every other string has the same character at i; stop at the first mismatch or when any string ends, and return the prefix up to i.
2. Complexity: O(S) time where S is the total number of characters (at worst n strings times the shortest length m), O(1) extra space besides the result.
3. Edge cases: an empty array returns an empty string, any empty string makes the answer empty, a single string is its own prefix, identical strings return the whole string.
4. Mention alternatives and their trade-offs: sort and compare only the first and last strings (O(n log n) comparisons), divide and conquer, binary search on prefix length, or a trie when many queries hit the same set.

Follow-up

• The set of strings changes and you get many prefix queries. What structure do you use?
• How would you find the longest common suffix instead?
• Does your solution handle Unicode and case-insensitive comparison?

Explain the differences between depth-first and breadth-first search algorithms.

Medium · Coding / Algorithms

Approach

1. DFS goes as deep as possible before backtracking, using recursion or an explicit stack; BFS explores level by level using a queue. Both are O(V + E) time with an adjacency list.
2. Space differs: BFS holds a whole frontier (up to the graph's width), DFS holds the current path (up to its depth); deep recursion can hit stack limits (Python's default recursion limit is about 1000), so iterative DFS is safer on large inputs.
3. Use BFS for shortest paths in unweighted graphs and level-order problems; use DFS for cycle detection, topological sort, connected components and backtracking searches.
4. On general graphs keep a visited set to avoid infinite loops on cycles; be ready to write both on a grid or adjacency list in your primary language.

Follow-up

• How would you find the shortest path if edges had weights?
• Write DFS iteratively and explain how its visit order can differ from the recursive version.
• How would you detect a cycle in a directed graph?

What is a hash table, and how would you use it in a project?

Medium · Coding / Algorithms

Approach

1. Explain the mechanism: a hash function maps a key to a bucket index in an array; collisions are handled by chaining (a list per bucket) or open addressing (probing for another slot).
2. Complexity: average O(1) insert, lookup and delete; worst case O(n) when many keys collide; the table resizes when the load factor passes a threshold, giving amortised O(1) inserts.
3. Key requirements: keys should be immutable and equality must agree with hashing (in Java override equals and hashCode together; in C# Equals and GetHashCode); iteration order is not guaranteed in general (Java HashMap) unless the structure promises it (LinkedHashMap, Python dict insertion order).
4. Give a real project use: caching lookups by ID, deduplicating records, counting occurrences, grouping rows by a key, or turning an O(n squared) nested search into O(n).

Follow-up

• Implement a simple hash map with chaining and resizing.
• What goes wrong if a mutable object used as a key changes after insertion?
• How do you use a hash map safely from multiple threads?

Can you provide a solution to a common sorting algorithm and explain its time complexity?

Medium · Coding / Algorithms

Approach

1. Pick one and write it fully: merge sort (split, sort halves recursively, merge with two pointers) or quicksort (choose a pivot, partition, recurse on both sides).
2. State the complexities: merge sort O(n log n) in every case, O(n) extra space, stable; quicksort O(n log n) on average, O(n squared) worst case with bad pivots (sorted input with a first-element pivot), in place, not stable; randomised or median-of-three pivots make the worst case unlikely.
3. Compare with others: insertion sort is O(n squared) but fast on small or nearly sorted input; comparison sorts cannot beat O(n log n); counting or radix sort reach linear time for bounded integer keys.
4. Know what your language's library uses: Python's sort and Java's sort for objects use Timsort (stable), Java uses a dual-pivot quicksort for primitives, and .NET's Array.Sort uses introsort (not stable).

Follow-up

• How would you sort a file too large to fit in memory?
• When does stability matter in a real application?
• Find the kth smallest element without fully sorting the array.

Describe the considerations you take into account when designing a database schema.

Medium · System Design / Architecture

Approach

1. Start from the entities and the access patterns: which queries run most often, which writes must be transactional, and how much data each table will hold.
2. Normalise to remove update anomalies (roughly third normal form), then denormalise deliberately only for a measured read need; use foreign keys and primary keys, and decide surrogate versus natural keys.
3. Push integrity into the database: NOT NULL, UNIQUE, CHECK (lease end after start), and for overlap rules such as two active leases on one unit, an exclusion constraint in Postgres or a guarded transaction elsewhere. Store money as DECIMAL, never float, and timestamps with time zone.
4. Design indexes for the real queries (composite index column order matches filter and sort), and plan for history: effective-dated rows or an audit table for leases and rent changes, soft deletes where records must be retained.
5. Plan schema changes as backward-compatible migrations (expand, backfill, switch reads, then contract) so deploys do not need downtime.

Follow-up

• How would you prevent two overlapping active leases on the same unit?
• How do you change a column type on a large table without downtime?
• When would you denormalise, and how do you keep the copy consistent?

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 most proficient in, and how have you used them in past projects?

Medium · Technical / Domain Questions

Approach

1. Lead with one primary language from the ones this role lists (Java, Python or C#) instead of reciting every language you have touched, then name secondary ones with an honest depth level.
2. Anchor the primary language in one project: what you built, the framework and libraries (for example Spring Boot, Django or FastAPI, ASP.NET Core), the database, and one measurable outcome.
3. Show depth with one or two language-specific details you have actually used: Java's equals/hashCode contract and concurrency utilities, Python's generators, type hints and packaging, or C# async/await and LINQ.
4. Say why the language fitted that project (ecosystem, team skills, performance, existing codebase) so the answer shows judgment rather than preference.

Follow-up

• What do you find weakest about your primary language, and how do you work around it?
• If you joined a team using one of the other listed languages, how would you get productive in it?
• Explain a language feature you relied on in that project and a bug it caused or prevented.

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

Medium · Technical / Domain Questions

Approach

1. Choose a problem with a genuine technical root cause (a race condition, a slow query, a memory leak, an integration that dropped data), not a scheduling or people problem.
2. Use STAR but spend most of the time on the Action: the hypotheses you formed, the evidence you collected (logs, profiler, query plan, metrics), what you ruled out, and why you chose the fix you chose.
3. Quantify the Result: latency before and after, error rate, hours saved, incidents prevented, and say how you verified the fix in production.
4. Say what you changed to stop it recurring (a regression test, an alert, a code review rule) and use 'I' for your own work so your contribution is clear.

Follow-up

• What alternatives did you consider and why did you reject them?
• How did you confirm your change caused the improvement and not something else?
• What would you do differently if the same problem appeared tomorrow?

How do you ensure code quality and maintainability in your projects?

Medium · Technical / Domain Questions

Approach

1. Describe layers you actually run: small pull requests with code review on Git, automated tests in CI that block merges, linters and static analysis (Checkstyle or SpotBugs for Java, ruff or pylint and mypy for Python, Roslyn analyzers for C#), and consistent formatting.
2. Explain the testing mix: many fast unit tests, integration tests against a real database for data access code, a few end-to-end tests on the critical paths; treat coverage as a floor, not the goal.
3. Name design habits that keep code maintainable: single responsibility, dependency injection so business logic is testable, clear module boundaries, and documenting non-obvious decisions (for example in architecture decision records).
4. Give one concrete example where one of these practices caught a defect or made a later change easy, and one trade-off you accepted (shipping with known technical debt that you then tracked and paid down).

Follow-up

• How do you handle a reviewer who disagrees with your approach?
• You have to change a module with no tests. What do you do first?
• When is it acceptable to skip tests or take on technical debt?

How would you design a property management application from scratch?

Medium · System Design / Architecture

Approach

1. Fix scope first: users are residents, property managers and maintenance staff; core flows are units and leases, rent payments, maintenance requests and notifications. Say which you will design in depth and what you leave out.
2. Model the core entities: Property, Unit, Resident, Lease (unit, residents, start and end dates, rent), Payment, MaintenanceRequest (status: open, assigned, in progress, done), Vendor. Use a relational database because leases and payments need transactions and constraints.
3. Sketch the architecture: web and mobile clients, an API layer with authentication and role-based access scoped by property (a resident sees only their lease, a manager only their portfolio), a modular backend service, object storage for documents and photos, a queue for notifications and emails.
4. Handle payments with an external payment processor, idempotency keys so a double-submitted payment is charged once, and webhook reconciliation into a payment ledger; expect load spikes around rent due dates and cache read-heavy views.
5. Start as a modular monolith and name the seam you would split later (payments or notifications), plus a read replica or separate store for portfolio reporting so analytics queries do not slow the transactional path.

Follow-up

• A resident clicks Pay twice and the processor times out once. How does your design avoid a double charge?
• How would you build a dashboard showing occupancy and overdue rent across hundreds of properties?
• How would maintenance technicians use this with poor connectivity inside buildings?

Explain how you would approach designing a system that handles high traffic volumes.

Medium · System Design / Architecture

Approach

1. Quantify before designing: requests per second at peak versus average, read/write ratio, payload sizes, and latency target (for example a p99 goal); the read path and write path usually have different bottlenecks.
2. Make the application tier stateless behind a load balancer with autoscaling; serve static assets through a CDN; add caching (cache-aside in Redis with TTLs and explicit invalidation on writes) for hot reads.
3. Scale the database in order: indexes and query fixes, connection pooling, read replicas for read-heavy traffic, then partitioning or sharding by a key that keeps common queries on one shard.
4. Move slow or bursty work to queues with workers, and protect the system with rate limiting, timeouts, retries with backoff and graceful degradation.
5. Name what you would monitor (p50 and p99 latency, error rate, saturation, queue depth) and how you would load test before a known peak.

Follow-up

• A popular cache key expires and thousands of requests hit the database at once. What do you do?
• A user updates data and immediately reads a stale value from a replica. How do you fix that?
• Which component breaks first when traffic grows tenfold?

What are the key principles of microservices architecture, and when would you use them?

Medium · System Design / Architecture

Approach

1. State the principles: each service owns one business capability and its own data, deploys independently, communicates through versioned APIs or events, and fails without taking others down.
2. Name the costs honestly: network calls instead of function calls, no cross-service transactions, harder debugging (needing distributed tracing and correlation IDs), more infrastructure and on-call overhead.
3. Give the decision rule: use microservices when separate teams need to ship independently, components have very different scaling or reliability needs, and CI/CD and observability are mature; otherwise a modular monolith with clean module boundaries is usually the better start.
4. Describe migration with the strangler fig pattern: route one capability at a time to a new service behind the existing interface, and add resilience patterns (timeouts, circuit breakers, bulkheads) from the first split.

Follow-up

• How would you decide where to cut the first service out of a monolith?
• How do services that own separate databases support a report that needs data from all of them?
• One downstream service becomes slow and the whole system degrades. How do you contain it?

How do you approach system integration and ensuring data consistency across services?

Medium · System Design / Architecture

Approach

1. Choose the integration style per interaction: synchronous REST or gRPC when the caller needs an answer now, asynchronous events through a broker when it does not; avoid two-phase commit across services.
2. Use the transactional outbox: write the business change and an outbox row in the same local transaction, then publish from the outbox, so a crash cannot record the change without emitting the event.
3. Make consumers idempotent (store processed message IDs or use natural idempotency keys), since brokers deliver at least once; use retries with exponential backoff and jitter, and a dead-letter queue for poison messages.
4. For multi-step business flows use a saga with compensating actions (for example reverse a recorded payment if the ledger update fails), and run periodic reconciliation jobs to detect and repair drift.
5. Protect contracts with versioned schemas and consumer-driven contract tests so one team's change does not silently break another service.

Follow-up

• The same event is delivered twice. What happens in your design?
• A consumer is down for a day. How does it catch up, and what about ordering?
• How would you detect that two systems disagree about a resident's balance?

If you were given a legacy system to improve, what would be your first steps?

Medium · Problem-solving / Case Studies

Approach

1. Understand before changing: talk to the system's users and maintainers about pain points, read the code and data model, map its dependencies and integrations, and get it building and deploying reliably.
2. Make change safe: add characterisation tests that capture current behaviour, plus logging and monitoring, before refactoring.
3. Choose targets by evidence: incident history, slowest or most changed areas, user complaints; rank by value and risk.
4. Improve incrementally, not by a big-bang rewrite: refactor in small steps, or use the strangler fig pattern to replace one piece at a time behind the existing interface, keeping data migrations reversible.

Follow-up

• When is a full rewrite justified?
• The system has no tests and no documentation. Where exactly do you start?
• How do you convince stakeholders to fund work that adds no visible feature?

Discuss how you would gather requirements for a new feature from stakeholders.

Medium · Problem-solving / Case Studies

Approach

1. Identify every stakeholder group (for property software: residents, property managers, maintenance staff, finance or operations) and talk to each, ideally watching how they do the task today.
2. Ask about the problem and current workflow rather than the requested solution; capture the underlying need, constraints and how success will be measured.
3. Write user stories with acceptance criteria, state non-goals explicitly, and validate with a wireframe or prototype built with UX before committing to the full build.
4. Resolve conflicts between stakeholders by tying options to the agreed goal and getting the product owner to decide; then iterate in short cycles and review with users after each increment.

Follow-up

• Two stakeholder groups want contradictory behaviour. What do you do?
• Requirements change halfway through the sprint. How do you handle it?
• How do you gather requirements from users who are not technical?

How do you approach testing and validation of new software features?

Medium · Problem-solving / Case Studies

Approach

1. Plan testing alongside the feature: acceptance criteria become test cases, including boundary values, invalid input, permissions and empty states.
2. Use a layered approach: unit tests for logic, integration tests against a real database and real HTTP boundaries (for example with Testcontainers), contract tests for APIs other teams consume, and a few end-to-end tests on critical paths such as payments.
3. Run everything in CI on each pull request, validate in a staging environment with realistic data, and release behind a feature flag or to a small group first.
4. Validate after release with monitoring and with the stakeholders who asked for the feature; keep the flag as a quick rollback until metrics look right.

Follow-up

• How do you deal with flaky tests?
• How would you test a rent payment flow that calls an external processor?
• How much test coverage is enough?

How would you approach debugging a complex software issue?

Medium · Problem-solving / Case Studies

Approach

1. Reproduce first, or define exactly when it happens: inputs, environment, frequency, first occurrence. Then check what changed around that time (deploys, config, data, dependencies).
2. Gather evidence before theorising: logs, metrics, traces, error reports; verify the instrumentation itself is correct.
3. Narrow systematically: bisect commits (git bisect), disable components or feature flags, or shrink the input to a minimal reproduction; form one hypothesis at a time and test it.
4. Fix the root cause rather than the symptom, add a regression test that fails without the fix, and record what happened so the team can prevent the class of bug.
5. Name the hard cases: intermittent failures (race conditions, timeouts) need more logging or stress tests; production-only issues need comparison of environment, data volume and configuration.

Follow-up

• You cannot reproduce the bug locally. What next?
• How do you tell a cause from a coincidence, such as a deploy that happened at the same time?
• Walk me through a real bug you debugged this way.

Suggested practice checklist

Each day targets one group of the reported questions for this role, from your opening story through coding fundamentals, data modelling and design, engineering practice and the management conversations, and ends with something you can rehearse aloud.

Day 1 — Your background story and the screening questions

• Write a short walkthrough of your experience naming your primary language (Java, Python or C#), one API you designed and one database you worked with, ending on why this role.
• Outline answers to the languages question and the cloud services question, each anchored in a single project with named frameworks or AWS/Azure services and a result.
• Outline the learning-a-new-technology story in STAR form, and list three questions to ask in the phone screen about team, project area and hybrid setup.

Deliverable: A spoken background walkthrough, two anchored technical answers, one STAR story and three questions for the screen.

Day 2 — Linked lists, strings and sorting

• Write iterative and recursive linked list reversal in your primary language and trace both on an empty list, one node and three nodes.
• Write the longest common prefix by vertical scanning, then state its complexity and the sort-first alternative.
• Write merge sort and quicksort from memory and list their time, space and stability properties side by side.

Deliverable: Three working solutions with traced edge cases and a one-page comparison table of sorting algorithms.

Day 3 — Graphs and hash tables

• Write BFS and iterative DFS on an adjacency list and on a grid, and use BFS to return a shortest path in an unweighted graph.
• Write a small hash map with chaining and resizing, then explain load factor, collisions and the equals/hashCode contract aloud.
• Prepare one example from your own work where a hash map replaced a nested loop.

Deliverable: BFS and DFS implementations, a working hash map, and a spoken explanation of both topics with a project example.

Day 4 — Data modelling and the property management design

• Write the schema for a property management application: properties, units, residents, leases, payments and maintenance requests, with keys, constraints and indexes.
• Add the rule preventing overlapping active leases on a unit and the money and timestamp types you chose, and justify each.
• Practise a join-heavy query against your schema and check that one-to-many joins do not inflate totals.
• Talk through the full application design aloud: clients, API with role-based access, database, payments with idempotency keys, notifications queue.

Deliverable: A schema diagram with constraints, one checked aggregate query, and a recorded walkthrough of the application design.

Day 5 — Scale, services and data consistency

• Extend the day 4 design for a traffic spike: caching, read replicas, queues and rate limiting, naming what breaks first.
• Write a one-page comparison of a modular monolith and microservices for this application, with the point at which you would split out a service.
• Sketch the outbox pattern and an idempotent consumer for a payment event, including retries and a dead-letter queue.

Deliverable: A scaled design sketch, a monolith-versus-microservices page and an outbox/idempotency diagram.

Day 6 — Engineering practice with real examples

• For the code quality and testing questions, list the review, CI, static analysis and test layers you have actually used and attach one concrete example to each answer.
• Write your debugging sequence as numbered steps and attach a real bug you found with it; do the same for your approach to a legacy system.
• Outline the requirements-gathering answer around stakeholder groups, user stories with acceptance criteria and a prototype, plus your challenging technical problem story in STAR form.

Deliverable: Six spoken answers, each with a named example from your own work.

Day 7 — Behavioral stories and the management conversations

• Write STAR stories for the difficult team member, prioritisation, initiative, tight deadline, project you led and limited-information decision prompts, each with a numeric result.
• Rehearse each story aloud in about two minutes, then answer one follow-up per story without notes.
• Write and rehearse your future goals answer and a non-technical explanation of one system you built.

Deliverable: Six rehearsed STAR stories with follow-up answers, a future goals answer and a non-technical system explanation.

Behavioural preparation

Candidates report that the later stage involves managers and project stakeholders and centres on past experience and future goals, with communication, soft skills and behavioral interviewing among the reported topics. For this role, prepare stories that show you working with product, design and non-technical colleagues on software people use, each told in the first person with a measured result.

1. How do you manage differing opinions during team discussions?
2. Describe a situation where you had to present technical information to a non-technical audience.

Describe your experience with cloud services and how you have implemented them in your work.

Medium · Technical / Domain Questions

Approach

1. Name concrete services on AWS or Azure (the platforms this role lists) instead of saying 'the cloud': compute (Lambda, ECS, Azure Functions, App Service), storage (S3, Blob Storage), managed databases (RDS, Azure SQL), queues (SQS, Service Bus).
2. Walk through one deployment end to end: how code got there (CI/CD pipeline), how infrastructure was defined (Terraform, CloudFormation, Bicep or ARM), and how it was monitored (CloudWatch, Application Insights).
3. Cover security and cost decisions you personally made: least-privilege IAM roles, secrets in Secrets Manager or Key Vault rather than config files, right-sizing or autoscaling to control spend.
4. Close with a result and one thing that went wrong in production and how you fixed it; if your cloud experience is light, say so and describe what you did use and how you would ramp up.

Follow-up

• How did you manage secrets and credentials in that setup?
• What would happen to your service if the managed database became unavailable, and how would you recover?
• How did you keep the cloud bill under control?

Can you discuss a time when you had to learn a new technology quickly for a project?

Medium · Technical / Domain Questions

Approach

1. Pick a case with a real deadline where the new technology was on the critical path (a framework, a cloud service, a language, a database) and say why you could not avoid it.
2. Show the learning method: official docs and tutorials for the core model, a small time-boxed spike to prove the riskiest part, reading existing code or examples, and asking someone experienced targeted questions.
3. State what you shipped with it and the result, and how you reduced risk while still learning (code review by someone who knew it, feature flag, extra tests).
4. Close with what you would do differently; the story fails if you learned something but nothing shipped, or if the learning is described only as 'I read a lot'.

Follow-up

• What mistake did you make while learning it, and how did you find it?
• How did you decide you knew enough to start building?
• How would you onboard a teammate onto the same technology?

Tell me about a time when you had to collaborate with a difficult team member.

Medium · Behavioral / Leadership

Approach

1. Describe the behaviour, not the person's character: missed reviews, dismissive comments, work changed without discussion, and what it was costing the project.
2. Show your actions in order: a private one-to-one conversation to understand their view, finding the underlying concern (workload, unclear ownership, disagreement on approach), and agreeing a concrete working arrangement.
3. Give the result with evidence (the feature shipped, review turnaround improved, the working relationship held) and what you would do earlier next time.
4. The story sinks if it is mainly about blaming the colleague, if you escalated before talking to them, or if nothing was resolved.

Follow-up

• What would you have done if the conversation had not changed anything?
• What did you learn about how you yourself contributed to the friction?
• How do you handle differing opinions during team discussions in general?

How do you prioritize tasks when managing multiple projects?

Medium · Behavioral / Leadership

Approach

1. Give your actual method: list the work, rank by impact and urgency, account for deadlines and dependencies (what blocks others first), and estimate effort.
2. Show that you make trade-offs visible: when everything cannot fit, you tell stakeholders what will slip and agree it with them rather than quietly working late on everything.
3. Illustrate with one real period where you juggled several projects: what you chose to do first, what you deferred, and how it turned out.
4. Mention the tools or rituals you use to keep it current (a sprint backlog, a weekly priority check with your manager) without making the tool the answer.

Follow-up

• Two managers each say their request is the top priority. What do you do?
• Tell me about a time your prioritisation turned out to be wrong.
• How do you protect time for maintenance work against feature requests?

Describe a situation where you took initiative to solve a problem.

Medium · Behavioral / Leadership

Approach

1. Pick a problem nobody had assigned to you that you noticed yourself: a flaky deployment, a manual report, a recurring support issue, missing monitoring.
2. Show how you confirmed it was worth solving with evidence (hours lost, incidents, complaints) before investing time, and how you got buy-in from your lead or the owning team.
3. Describe what you built or changed and how you kept it small enough to land, then the measured result.
4. Avoid stories where initiative meant going around people or ignoring assigned work; the point is judgment as well as drive.

Follow-up

• How did you fit this alongside your assigned work?
• Who disagreed, and how did you convince them?
• What happened to the solution after you moved on?

How do you handle tight deadlines and pressure?

Medium · Behavioral / Leadership

Approach

1. Use one specific deadline, not a general claim that you work well under pressure: what was due, why it was tight, and what was at stake.
2. Show the decisions: breaking the work down, cutting or deferring scope rather than skipping tests, raising the risk early with the people affected, and asking for help where it unblocked the critical path.
3. State the outcome honestly, including what was deferred and when it was delivered.
4. Add what you changed afterwards to avoid the same crunch (earlier estimates, buffer, splitting releases).

Follow-up

• Tell me about a deadline you missed. What happened?
• What did you refuse to compromise on, and why?
• How do you tell your manager a deadline is at risk?

Can you give an example of a successful project you led and the impact it had?

Medium · Behavioral / Leadership

Approach

1. Define what 'led' meant: you owned the plan, the technical direction, the breakdown of work, or the coordination with stakeholders; say team size and your role clearly.
2. Walk through two or three decisions you made as lead (scope, architecture, sequencing) and why.
3. Quantify the impact on users or the business: time saved for staff, errors reduced, adoption, revenue or cost; if a metric is approximate, say how you estimated it.
4. Include one thing that went wrong and how you handled it; a lead story with no setbacks sounds rehearsed.

Follow-up

• What would you do differently if you led it again?
• How did you handle a team member who was struggling?
• How did you measure the impact after launch?

Describe a time you had to make a difficult decision with limited information.

Medium · Problem-solving / Case Studies

Approach

1. Set up what was unknown and why waiting was costly: a production issue, a vendor choice, a design call before requirements were final.
2. Show your reasoning: what information you could get quickly, the cost of being wrong versus the cost of delay, and whether the decision was reversible.
3. Describe how you limited risk: a reversible first step, a feature flag, a rollback plan, a checkpoint to revisit once more data arrived, and who you informed.
4. Give the outcome and what you learned when the missing information did arrive, including if you were partly wrong.

Follow-up

• What information would have changed your decision?
• How did you communicate the uncertainty to stakeholders?
• Would you make the same decision today?