A Software Engineer at Underdog Fantasy plays a pivotal role in shaping the future of fantasy sports through innovative software solutions. As a member of a dynamic engineering team, you will contribute to the design, development, and optimization of platforms that enhance user engagement and drive business growth. This position is crucial in delivering seamless experiences to millions of users who rely on our applications for fantasy sports, betting, and gaming. Your work will directly impact the quality and performance of our products, including our flagship fantasy sports platforms. You will face challenges that require not only technical expertise but also a deep understanding of user needs and market trends. This role offers the opportunity to work on complex systems that scale to accommodate a growing user base, making it both challenging and rewarding. Candidates can expect to engage with cutting-edge technologies and methodologies while collaborating with cross-functional teams to solve real-world problems in the fantasy sports domain. Your contributions will be integral to maintaining our competitive edge and ensuring that remains at the forefront of the industry. Underdog Fantasy
Phone Screen
reportedInitial phone screen conducted by a recruiter to evaluate candidate fit.
What to demonstrate
- Initial phone screen conducted by a recruiter to evaluate candidate fit
- Depth in Coding Assessments / Coding Challenges
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 Interviews
reportedOne or more technical interviews assessing coding skills and technical knowledge.
What to demonstrate
- One or more technical interviews assessing coding skills and technical knowledge
- Depth in Coding Assessments / Coding Challenges
How to prepare
- Answer aloud and timed: Describe your experience with microservices architecture.
- Answer aloud and timed: What is your approach to API design and integration?
PracHub editorial advice for the preparation topics above.
Understand the Product
Familiarize yourself with Underdog Fantasy's offerings and how they differ from competitors. Being able to discuss the product will demonstrate your interest and alignment with the company’s mission.
Practice Coding
Use platforms like LeetCode or HackerRank to sharpen your coding skills. Focus on algorithms, data structures, and system design problems to prepare for technical interviews.
Prepare for Behavioral Questions
Reflect on your past experiences and prepare concrete examples that highlight your skills and achievements. Use the STAR (Situation, Task, Action, Result) method to structure your answers.
Ask Questions
Show your engagement and interest in the company by preparing insightful questions for your interviewers. This not only demonstrates your enthusiasm but also helps you assess if the company is a good fit for you.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Explain the difference between synchronous and asynchronous programming.
Explain the difference between synchronous and asynchronous programming.
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?
How does the garbage collection mechanism work in C#?
How does the garbage collection mechanism work in C#?
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?
Write a function to reverse a linked list.
Write a function to reverse a linked list.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Solve a problem involving data structures such as trees or graphs.
Solve a problem involving data structures such as trees or graphs.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Explain your reasoning while solving a coding challenge.
Explain your reasoning while solving a coding challenge.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Discuss how you would approach writing unit tests for your code.
Discuss how you would approach writing unit tests for your code.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
What data structures would you use to implement a cache system?
What data structures would you use to implement a cache system?
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Discuss the trade-offs between SQL and NoSQL databases for a new application.
Discuss the trade-offs between SQL and NoSQL databases for a new application.
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- Handle the rows that do not match: that is usually the actual question.
Follow-up
- How does the query change if that join becomes one-to-many?
- What happens to this when the table is ten times larger?
Find version gaps and relay lag with window functions
outbox_event holds event_id, aggregate_type, aggregate_id, aggregate_version, event_type, payload, status ('pending','published','dead'), attempts, created_at, published_at. A projection is missing rows and you must decide whether the relay skipped events or the consumer dropped them. Write three queries over the last seven days: one listing every aggregate_id whose published aggregate_version sequence has a hole, one giving per-day counts with a running total, and one returning the newest published event per aggregate. For each, say where the window function is evaluated relative to WHERE and LIMIT. PostgreSQL 16.
Approach
- Gaps: compute lead(aggregate_version) OVER (PARTITION BY aggregate_id ORDER BY aggregate_version) in a subquery, then filter next_version <> aggregate_version + 1 in the outer query. Window functions are evaluated after WHERE, GROUP BY and HAVING and before the outer ORDER BY and LIMIT, so the predicate cannot sit in the same WHERE clause and PostgreSQL 16 has no QUALIFY.
- Say what the seven-day filter does to the answer: it truncates every partition, so the first row per aggregate has no predecessor inside the window and a hole spanning the boundary is invisible. Widen the window, or join to resource.version as the authority for the true maximum.
- Running total: SELECT date_trunc('day', created_at) AS d, count() AS n, sum(count()) OVER (ORDER BY date_trunc('day', created_at) ROWS UNBOUNDED PRECEDING). An aggregate inside a window call is legal because grouping runs before windowing. The grouping key is unique per row here so ROWS and RANGE agree, but write the frame anyway — over ungrouped rows with tied timestamps the default RANGE frame pulls in every peer row and the total jumps.
- Newest per aggregate: DISTINCT ON (aggregate_id) ... ORDER BY aggregate_id, aggregate_version DESC is the cheap PostgreSQL-only form when an index matches that order; row_number() OVER (PARTITION BY aggregate_id ORDER BY aggregate_version DESC) = 1 is the portable form and needs a subquery for the same evaluation-order reason as the gap query.
Follow-up
- Relay failover redelivers events. Does a duplicate break the gap query, and how would you detect one from this table alone?
- Turn the gap check into a continuous monitor rather than a query someone runs after an incident. What does it watch?
Describe your experience with microservices architecture.
Describe your experience with microservices architecture.
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 is your approach to API design and integration?
What is your approach to API design and 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?
Discuss a challenging technical problem you faced and how you resolved it.
Discuss a challenging technical problem you faced and how you resolved it.
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?
Design a scalable system for a fantasy sports application.
Design a scalable system for a fantasy sports 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?
How would you handle data consistency in a distributed system?
How would you handle data consistency in a distributed system?
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?
Describe how you would approach the design of a new feature, including any architectural patterns you would co
Describe how you would approach the design of a new feature, including any architectural patterns you would consider.
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 considerations would you have for performance optimization in your designs?
What considerations would you have for performance optimization in your designs?
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?
If tasked with improving an existing feature, how would you approach it?
If tasked with improving an existing feature, how would you approach it?
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?
Present a solution to a hypothetical scenario involving user data privacy.
Present a solution to a hypothetical scenario involving user data privacy.
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 prioritize feature requests from stakeholders?
How would you prioritize feature requests from stakeholders?
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 steps would you take to ensure quality in your code?
What steps would you take to ensure quality in your code?
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?
Describe your method for debugging a complex application issue.
Describe your method for debugging a complex application issue.
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 Underdog Fantasy candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Underdog Fantasy loop
- Write out the reported sequence: Phone Screen, Technical Interviews.
- For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.
Deliverable: A one-page map of the 2 reported rounds, with the weakest marked.
02Work Coding Assessments / Coding Challenges
- Spend the session on Coding Assessments / Coding Challenges, which Underdog Fantasy candidates report being tested on.
- Write one worked example in Coding Assessments / Coding Challenges and time yourself on it.
Deliverable: One timed worked example in Coding Assessments / Coding Challenges.
03Work System Design
- Spend the session on System Design, which Underdog Fantasy candidates report being tested on.
- Write one worked example in System Design and time yourself on it.
Deliverable: One timed worked example in System Design.
04Work Async Programming (Asynchronous Approaches)
- Spend the session on Async Programming (Asynchronous Approaches), which Underdog Fantasy candidates report being tested on.
- Write one worked example in Async Programming (Asynchronous Approaches) and time yourself on it.
Deliverable: One timed worked example in Async Programming (Asynchronous Approaches).
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: Explain the difference between synchronous and asynchronous programming.
- Answer aloud, timed: How does the garbage collection mechanism work in C#?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: System Design / Architecture
- Answer aloud, timed: Design a scalable system for a fantasy sports application.
- Answer aloud, timed: How would you handle data consistency in a distributed system?
Deliverable: Spoken answers to 2 reported System Design / Architecture question(s), under time.
07Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Describe a time when you had to lead a project under tight deadlines.
- Answer aloud, timed: How do you handle conflicts within a team?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership 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.
Describe a time when you had to lead a project under tight deadlines.
Describe a time when you had to lead a project under tight deadlines.
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 conflicts within a team?
How do you handle conflicts within a team?
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?
Give an example of how you’ve contributed to a positive team environment.
Give an example of how you’ve contributed to a positive team environment.
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?
Discuss a time when you had to adapt to significant changes at work.
Discuss a time when you had to adapt to significant changes at work.
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?
What motivates you to excel in your role?
What motivates you to excel in your role?
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
Describe a time when you had to lead a project under tight deadlines.
- 02
How do you handle conflicts within a team?
- 03
Give an example of how you’ve contributed to a positive team environment.
- 04
Discuss a time when you had to adapt to significant changes at work.
How difficult is the interview process, and how much preparation time is typical?
The interview process is moderate in difficulty, with a blend of technical and behavioral assessments. Candidates typically spend several weeks preparing to ensure they are well-versed in relevant technologies and concepts.
Underdog Fantasy Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates demonstrate a strong technical foundation, effective problem-solving skills, and the ability to communicate their thought processes clearly. Additionally, alignment with the company’s values and culture is critical.
Underdog Fantasy Software Engineer candidate reports ↗What is the typical timeline from initial screen to offer?
Generally, candidates can expect a timeline of 2-4 weeks from the initial phone screen to receiving an offer, although this may vary based on the team’s availability.
Underdog Fantasy Software Engineer candidate reports ↗What is the company culture like at Underdog Fantasy?
The culture at Underdog Fantasy emphasizes collaboration, innovation, and user-centric design. Engineers are encouraged to share ideas and contribute to team success.
Underdog Fantasy Software Engineer candidate reports ↗Are remote work or hybrid expectations common for this role?
Underdog Fantasy supports flexible working arrangements, including remote and hybrid options, depending on team dynamics and project needs.
Underdog Fantasy Software Engineer candidate reports ↗What topics does Underdog Fantasy test in interviews?
Underdog Fantasy interviews most often cover DBT (Data Build Tool), UX/UI Design, MVVM Architecture, Coding Assessments / Coding Challenges, and Product Management (PM) Fundamentals. The exact emphasis depends on the specific role you apply for.
Underdog Fantasy 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.
- 01Underdog Fantasy 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
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