Buck · Software Engineer
Updated · 2026-10-02

Buck Software Engineer
Interview Guide

THE 60-SECOND BRIEF

Candidate reports describe a Buck Software Engineer as someone who builds, tests and maintains software applications that Buck uses internally and delivers as part of its client offerings. The work is described as cross-functional: you would work with product managers, UX designers and other engineers on product design, functionality and user experience, and take part in code reviews. The reports do not name specific products, customers or teams, so use the recruiter screen to ask which team the role sits in and which of the listed languages (Java, C# or Python) that team uses.

This guide is for candidates interviewing for the Software Engineer role at Buck. It covers the four reported rounds (Initial Screening, Technical Assessment, Behavioral Assessment, Final Interviews), the reported object-oriented, SQL, design-pattern, troubleshooting, coding and behavioral questions, and the stack the requirements list: Java, C# or Python, SQL, and Agile and DevOps practices, with AWS, Azure, microservices and front-end frameworks as nice-to-haves.

Candidates report four stages, Initial Screening, Technical Assessment, Behavioral Assessment and Final Interviews, over roughly 3-5 weeks. Reported questions mix object-oriented design, SQL tuning, coding, troubleshooting and behavioral prompts.

SQL Query WritingObject-Oriented Programming (OOP)Interfaces

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Browse Software Engineer questions

See the practice prompts

15Practice promptsAcross five skill areas

The reported question set leans on fundamentals rather than puzzles. Four questions are about object-oriented design: the principles of OOP, interface versus abstract class, the SOLID principles, and design patterns with an example you have implemented yourself. One asks how to optimize a SQL query. Three are classic coding exercises: reverse a linked list, find the longest substring without repeating characters, and implement binary search while explaining its complexity. That mix means you need to write small pieces of correct code in your chosen language and also explain design reasoning out loud.

Two reported questions are open-ended problem-solving prompts: troubleshooting a performance issue in a web application, and approaching the design and implementation of a new feature requirement. Candidates also describe a technical story prompt (a challenging problem you resolved). For these, prepare a repeatable method rather than a memorised answer: measure first, narrow the layer (browser, network, application, database), then fix and verify. For feature design, clarify requirements, outline components and data model, then say how you would test and ship it.

The requirements candidates describe list Java, C# or Python, solid SQL, and Agile and DevOps experience, with AWS or Azure, microservices and front-end technologies as extras. Reported examples of more advanced questions include migrating a monolithic application to microservices and implementing CI/CD in your projects, so have a concrete project of your own ready to draw on for both.

The behavioral stage is reported as being about working with teams, and the prompts are about pressure, prioritizing across projects and team conflict. Prepare each as a real story in which you made a decision and can state the result. Reports describe loop length as roughly 3-5 weeks, though another report quotes 2-4 weeks, so confirm the timeline with your recruiter and plan your preparation to be ready for the technical stage first.

01

Initial Screening

reported

Candidates describe this first stage as a review of your application and qualifications. The reports give no further format detail, so treat it as a conversation where your background is matched against the requirements candidates list: Java, C# or Python, SQL, Agile and DevOps experience, and a computer science degree or related internship and work experience. Approach it by making your CV easy to connect to that stack, and use the call to ask what the Technical Assessment will look like.

What to demonstrate

  • How your experience maps to the languages and methodologies in the reported requirements
  • Your relevant internship or work history and education
  • Whether you can summarise your own projects clearly

How to prepare

  • Pick one project per listed skill (a Java, C# or Python service, a SQL-backed feature, an Agile or DevOps practice you used) and rehearse a short description of each
  • Write down your role in each project: what you personally built, tested or decided
  • Prepare questions for the recruiter: which team, which language, what the technical stage involves (live coding, discussion or both)
Buck Software Engineer candidate reports ↗
02

Technical Assessment

reported

Candidates describe this stage as technical interviews centred on coding and problem-solving. The reported questions that fit this format are the coding exercises (reverse a linked list, longest substring without repeating characters, binary search) and the problem-solving prompts (troubleshooting web application performance, designing a new feature), alongside the object-oriented and SQL fundamentals questions. Approach it by writing working code in one language, narrating your reasoning, and testing with edge cases.

What to demonstrate

  • Working code for standard data-structure and algorithm problems
  • Command of OOP, interface versus abstract class, SOLID and design patterns
  • SQL optimization reasoning
  • A structured approach to troubleshooting and feature design

How to prepare

  • Write the linked-list reversal, sliding-window substring and binary search solutions from scratch in your chosen language, then trace each on empty, single-element and duplicate-heavy inputs
  • Prepare a concrete example for interface versus abstract class and one SOLID principle, each shown in code
  • Take a slow query, read its execution plan and explain which index or rewrite helps and why
  • Rehearse a performance troubleshooting sequence out loud, from symptom to measured cause to verified fix
Buck Software Engineer candidate reports ↗
03

Behavioral Assessment

reported

Candidates describe this stage as a behavioral assessment of how you work with teams and how you fit the company's stated values. The reported prompts are about working under pressure, prioritizing across multiple projects and handling team conflict. Approach it by preparing a small set of real stories, each with a clear situation, your specific actions, the result and what you changed afterwards.

What to demonstrate

  • Collaboration and communication with teammates
  • Judgment under pressure and when priorities compete
  • How you handle disagreement within a team

How to prepare

  • Write one story each for the pressure, prioritization and conflict prompts, using first person singular and naming your own decisions
  • Attach a concrete outcome to each story: what shipped, what stayed stable, what you learned
  • Prepare an example of explaining progress or requirements to a non-technical stakeholder, since the reported evaluation areas include stakeholder communication
Buck Software Engineer candidate reports ↗
04

Final Interviews

reported

Candidates describe the final stage as time with engineers and managers, covering both skills and how you think. Reported material that fits it includes the challenging technical problem you resolved, approaching a new feature requirement, and the more advanced examples candidates mention: migrating a monolith to microservices and implementing CI/CD. Approach it by being ready to go deep on a real project of your own and to reason aloud through design trade-offs.

What to demonstrate

  • Depth on your own past technical work
  • Design reasoning for new features and architecture changes
  • Communication with both engineers and managers

How to prepare

  • Pick one project and be ready to cover the problem, alternatives you rejected, the failure you hit and the fix
  • Outline a monolith-to-microservices migration: pick a seam, extract one service, handle shared data, then roll out and roll back safely
  • Write down a CI/CD pipeline you have used or would build: build, test, artifact, deploy, and how a bad release is reverted
  • Have two or three questions for the engineers and managers about the team's stack and review process
Buck Software Engineer candidate reports ↗

PracHub editorial advice for the preparation topics above.

01

Reciting the OOP pillars and SOLID letters as definitions with no code

For each pillar and each SOLID principle, prepare a short example in your chosen language, ideally showing a violation and its fix, such as a class with two reasons to change split into two.

02

Answering interface versus abstract class with only 'an interface has no implementation'

Cover what each can hold (state, constructors, default methods), single versus multiple inheritance, and when you would choose each, and state the rule for your own language, since Java, C# and Python differ.

03

Saying 'add an index' to the SQL optimization question without evidence

Describe reading the execution plan, checking for full scans, unusable predicates (functions on indexed columns) and unnecessary columns or joins, then verifying the improvement by re-running the plan.

04

Off-by-one and loop-termination bugs in binary search, the sliding window or the linked-list reversal

Write each routine from memory with explicit invariants (a search range that shrinks every step, a window with no repeated characters, a saved next pointer before relinking), then trace empty, one-element and duplicate inputs by hand.

05

Guessing at fixes for the web performance question, such as 'add a cache', before measuring

Open with how you would reproduce and measure, narrow the layer (client, network, application, database), name the likely suspects for each, and confirm the fix with the same measurement.

Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.

12 technical prompts0 include a worked solution

Write a function to reverse a linked list.

medium
Coding / Algorithms

Write a function to reverse a linked list.

Approach
  1. Walk the list once with three pointers: prev = null, curr = head; on each step save next = curr.next, set curr.next = prev, then advance prev = curr and curr = next. When curr is null, prev is the new head, and I return it.
  2. Complexity: O(n) time and O(1) extra space. The recursive version (reverse the rest, then set head.next.next = head and head.next = null) is also O(n) time but uses O(n) call-stack space, so it can overflow the stack on very long lists.
  3. Edge cases to state and test: an empty list, a single node, two nodes. Also make sure the old head's next ends up null, or the list contains a cycle.
  4. Dry-run it on 1 -> 2 -> 3 aloud before calling it done; the common bug is overwriting curr.next before saving the next node.
Follow-up
  • Reverse only the nodes between positions m and n in one pass.
  • Reverse the list in groups of k nodes, leaving any final group shorter than k unchanged.
  • How would you reverse a doubly linked list, and what changes?

How would you find the longest substring without repeating characters?

medium
Coding / Algorithms

How would you find the longest substring without repeating characters?

Approach
  1. Clarify the character set (ASCII or full Unicode) and whether to return the length or the substring itself. Name the brute force: check every substring for duplicates, O(n^3), or O(n^2) when each start grows a set.
  2. Use a sliding window with a map from character to its last seen index. For each right index r with character c: if c was seen at an index >= left, move left to last[c] + 1; record last[c] = r; update best = max(best, r - left + 1).
  3. The max(left, last[c] + 1) guard matters: without it a character seen before the current window would move left backwards, as in "abba", where the correct answer is 2.
  4. Complexity: O(n) time, since each index is visited once and map operations are O(1) on average; O(min(n, alphabet size)) space, or a fixed array of 128 for ASCII.
  5. Test on the empty string (0), all-identical characters like "bbbb" (1), "abcabcbb" (3) and "pwwkew" (3, the substring "wke").
Follow-up
  • Return the longest substring that contains at most k distinct characters.
  • How would you return the substring itself, and which one if there is a tie?
  • What changes if the input arrives as a stream you can read only once?

Implement a binary search algorithm and explain its time complexity.

medium
Coding / Algorithms

Implement a binary search algorithm and explain its time complexity.

Approach
  1. Confirm the precondition: the array is sorted and supports random access. Iterative version: lo = 0, hi = n - 1; while lo <= hi, compute mid, return mid if a[mid] == target, set lo = mid + 1 if a[mid] < target, otherwise hi = mid - 1; return -1 once the loop ends.
  2. Compute mid as lo + (hi - lo) / 2 in Java or C#, because (lo + hi) / 2 can overflow int on very large arrays. Python integers do not overflow, so (lo + hi) // 2 is safe there.
  3. Complexity: each step halves the search range, so O(log n) comparisons in the worst case (about 20 for a million elements) and O(1) extra space iteratively. A recursive version uses O(log n) stack. Linear search is O(n), and sorting first only pays off if many lookups follow.
  4. Keep one invariant to avoid off-by-one errors: closed range [lo, hi] with lo <= hi, or half-open [lo, hi) with lo < hi and hi = mid. For duplicates, write the lower-bound variant that returns the first index with a[i] >= target, which is what Python's bisect_left does.
  5. Test the empty array, one element, a target below the first or above the last element, and a target that appears several times.
Follow-up
  • Find the first and last positions of a target that appears several times.
  • Search a sorted array that has been rotated at an unknown pivot.
  • How would you binary-search over possible answers, for example the minimum capacity to ship packages within d days?

The plan follows the reported loop: fundamentals and design first, then SQL, coding and troubleshooting, then behavioral stories and a full run-through. Pick one of Java, C# or Python on day 1 and use it throughout.

Small steps. Visible outcomes.0 / 7 completed
ONE WEEK · YOUR PACE

Prepare, practise & reflect

One practical outcome each day. Spend longer where you need it.

0 / 7 done
01Map the loop and choose your language
  • Write the four reported rounds on one page and, for each, list which reported question types belong to it and what you would ask the recruiter about its format.
  • Choose Java, C# or Python for all coding and design answers, and set up a project where you can run small programs and tests quickly.
  • Mark your weakest area among OOP and design, SQL, coding, troubleshooting and behavioral stories.

Deliverable: A one-page loop map with your chosen language and your ranked weak areas.

02OOP, interfaces and SOLID
  • Write a small program in your chosen language that shows encapsulation, inheritance, polymorphism and abstraction, then explain each aloud.
  • Build a comparison table of interface versus abstract class for your language, with one example where each is the better choice.
  • Take one class that violates a SOLID principle, refactor it, and explain the principle in your own words.

Deliverable: A runnable OOP sample, an interface-versus-abstract-class table, and a before-and-after SOLID refactor.

Practice prompt ↗Practice prompt ↗Practice prompt ↗
03Design patterns and feature design
  • Choose two patterns you have actually used, such as Strategy and Factory, and write a short description of the problem each solved in your code.
  • Take an imagined feature requirement and outline requirements, components, data model, API, testing and rollout.
  • Write bullet outlines for the monolith-to-microservices migration and CI/CD questions candidates mention.

Deliverable: Two pattern examples, one feature design outline and two outlines for the migration and CI/CD questions.

Practice prompt ↗Practice prompt ↗
04SQL optimization
  • Take a slow query on a table of your own, read its execution plan, and write down the changes (index, predicate rewrite, narrower select) and the plan after.
  • List the common reasons an index goes unused and how you would spot each in a plan.
  • Work through the PracHub keyset paging practice exercise and explain why it beats offset paging on large tables.

Deliverable: A before-and-after plan comparison for one query, plus a short list of reasons an index goes unused.

Practice prompt ↗Practice prompt ↗
05Coding exercises
  • Write iterative linked-list reversal from memory, then trace it on empty, one-node and multi-node lists.
  • Write the sliding-window longest-substring solution with a map of last-seen positions, and test it on repeated characters and an empty string.
  • Write binary search with a safe midpoint, state the O(log n) complexity and test missing values and duplicates.

Deliverable: Three working solutions in your chosen language with a test list covering the edge cases for each.

Practice prompt ↗Practice prompt ↗Practice prompt ↗
06Troubleshooting and your technical story
  • Write a step-by-step performance troubleshooting checklist for a web application, with what you would measure at each layer.
  • Choose your hardest technical problem and write its story: context, options considered, decision, result.
  • Say both answers aloud and cut anything that does not help the listener follow your reasoning.

Deliverable: A troubleshooting checklist and a one-page technical story you can deliver aloud.

Practice prompt ↗Practice prompt ↗
07Behavioral stories and full run-through
  • Write one story each for working under pressure, prioritizing across projects and a team conflict, in first person singular with a stated outcome.
  • Rehearse the three stories aloud and trim each to the situation, your actions and the result.
  • Do a final run through one OOP answer, one SQL answer, one coding problem and one story in the order a loop might ask them.

Deliverable: Three finished behavioral stories and a full mixed run-through of your weakest items.

Practice prompt ↗Practice prompt ↗Practice prompt ↗

Expand any day for tasks and deliverables. Your progress is saved on this device.

Candidates describe the behavioral stage as being about how you work with teams. The reported prompts cover pressure, prioritizing across projects and team conflict, and the reported evaluation areas add communicating progress to non-technical stakeholders. For a software engineer, that means stories about real engineering decisions, such as a release deadline, competing tickets or a code-review disagreement, each with a result.

Describe a time when you had to work under pressure. How did you handle it?

medium
Behavioral / Leadership

Describe a time when you had to work under pressure. How did you handle it?

Approach
  1. Choose a story where you personally made the calls under a real constraint, such as a release deadline, a production incident or an unexpected scope change. A story where you only worked longer hours shows effort, not judgment.
  2. State the situation in two sentences with the stakes (who was affected and by when), then spend most of the answer on what you did: how you triaged, what you cut or deferred, who you told, and what you refused to cut such as testing or a rollback plan.
  3. Show how you communicated while under pressure: a short status to the stakeholder, a request for help when you needed it, and an agreed definition of done for the reduced scope.
  4. End with the measurable result and one lasting change, for example a runbook, an automated check or an earlier warning, so the story shows you reduced the chance of repeating the pressure.
  5. Avoid a story where the pressure came from your own late start with no reflection on it, and avoid presenting a heroic overnight effort as the lesson.
Follow-up
  • What did you decide to cut, and who agreed to that?
  • How did you keep quality up while moving quickly?
  • What would you change so the same pressure does not recur?

How do you prioritize tasks when working on multiple projects?

medium
Behavioral / Leadership

How do you prioritize tasks when working on multiple projects?

Approach
  1. Answer with a method first, then prove it with one real example. A method might be: list everything, estimate effort, rank by impact and deadline, flag what blocks other people, and revisit the ranking when something changes.
  2. Use a concrete case with several competing items, for example a sprint feature, a customer-reported bug and a refactor. Say which you did first, which you deferred, and the reason in terms of impact, risk or who was waiting on you.
  3. Show how you handled conflicting asks: you made trade-offs visible to the people involved, asked them to decide between competing priorities, and agreed on dates in writing or on the team's board.
  4. Include saying no or renegotiating a deadline. Explain how you told the affected person and what you offered instead, such as a smaller first release.
  5. Close with the outcome and how you adjusted when a new urgent item arrived mid-sprint, since a fixed list that never changes sounds untested.
Follow-up
  • Two managers both say their project is the top priority. What do you do?
  • A production bug arrives in the middle of a sprint. How does your plan change?
  • Tell me about a time you got the order wrong and what it cost.

Can you give an example of how you handled a conflict within a team?

medium
Behavioral / Leadership

Can you give an example of how you handled a conflict within a team?

Approach
  1. Pick a conflict about substance, such as an architecture choice, a code review disagreement or a clash over scope, rather than a personality dispute. Describe both positions fairly in a sentence each.
  2. Explain what you did to understand the other person's reasoning first: asked what constraint they were optimizing for, then looked for shared goals, such as reliability or delivery date.
  3. Show how you resolved it with evidence rather than persistence: a small prototype, a benchmark, a test case or a comparison of options against agreed criteria. State who made the final call and how you reached it, and escalate only if the team could not settle it.
  4. Report the outcome honestly, including if your view did not win. Say how you committed to the chosen path afterwards and how the working relationship stood.
  5. Avoid casting the other person as the problem, and avoid a story where you simply turned out to be right and everyone adjusted.
Follow-up
  • What if the other person had been more senior than you?
  • What would you have done if the evidence had favoured their approach?
  • How was your working relationship with them afterwards?
  • 01

    Describe a time when you had to work under pressure. How did you handle it?

  • 02

    How do you prioritize tasks when working on multiple projects?

  • 03

    Can you give an example of how you handled a conflict within a team?

  • 04

    Tell me about a time you explained a technical trade-off or status to a non-technical stakeholder.

  • 05

    Describe a code review where you and a teammate disagreed, and how it ended.

PracHub preparation framework ↗
How many rounds is the Buck Software Engineer interview process?

Candidates report four stages: Initial Screening, Technical Assessment, Behavioral Assessment and Final Interviews. The reports describe the stages only briefly, so ask the recruiter what format each one takes, for example live coding versus discussion.

Buck Software Engineer candidate reports ↗
How long does the process take?

The loop is reported at roughly 3-5 weeks, and another report puts the process at 2-4 weeks depending on scheduling and the number of rounds. Treat it as a range and ask your recruiter for dates so you can pace your preparation.

Buck Software Engineer candidate reports ↗
Which programming language should I use?

The requirements candidates describe list Java, C# or Python. Pick the one you write most fluently, and be ready to explain object-oriented concepts such as interfaces and abstract classes in that language, since the rules differ between them. Ask the recruiter if the team expects a specific one.

PracHub Software Engineer practice ↗
What technical topics should I prepare?

The reported questions cover OOP principles, interface versus abstract class, SOLID, design patterns, SQL query optimization, performance troubleshooting, feature design, reversing a linked list, longest substring without repeating characters, and binary search. Candidates also mention microservices migration and CI/CD as more advanced examples.

PracHub Software Engineer practice ↗
Are there remote or hybrid options?

Candidate reports mention remote options that depend on the team and project. Confirm the arrangement for your specific team during the Initial Screening.

Buck Software Engineer candidate reports ↗
How should I prepare for the behavioral round?

Prepare real stories for the three reported prompts about pressure, prioritization and team conflict, in first person singular with a decision and a result in each. Add one story about explaining a technical topic to a non-technical stakeholder, since reports list stakeholder communication as an evaluation area.

PracHub Software Engineer practice ↗
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.