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Expedia (IT) Software Engineer Interview Guide

Expedia (IT) Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

As a Software Engineer at Expedia (IT), you will play a pivotal role in architecting, building, and scaling high-throughput travel platform applications that power seamless travel experiences worldwide. From powering global hotel and flight search engines to building robust partner integration APIs, customer self-service refund processors, and real-time pricing systems, software engineers at Expedia (IT) solve multi-faceted engineering challenges at an extraordinary scale. The software engineering team at Expedia (IT) operates across a wide spectrum of modern technologies, including backend cloud microservices, front-end web architectures, and real-time distributed systems. Engineers handle massive request volumes daily, where performance optimizations, system resilience, and clean, modular design directly impact millions of travelers and partner organizations across global markets.

This guide is scoped to a Software Engineer candidate at Expedia (IT).

Focus areas

  • React
  • System Design
  • Code Review (PR Review)

The Expedia (IT) interview process

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

Initial Screening Assessment

Automated online coding assessment or recruiter screen focusing on core computer science concepts and hands-on coding challenges.

What to demonstrate

  • Automated online coding assessment or recruiter screen focusing on core computer science concepts and hands-on coding challenges
  • Depth in React

How to prepare

  • Be able to walk your CV end to end in two minutes, and say why this company specifically.
  • Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Screening Call

For senior positions, a detailed technical or architectural screening call with an engineering manager.

What to demonstrate

  • For senior positions, a detailed technical or architectural screening call with an engineering manager
  • Depth in React

How to prepare

  • Be able to walk your CV end to end in two minutes, and say why this company specifically.
  • Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Virtual Evaluation Loop

Multiple focused sessions including algorithmic live coding, code reviews, system design, and behavioral interviews.

What to demonstrate

  • Multiple focused sessions including algorithmic live coding, code reviews, system design, and behavioral interviews
  • Depth in React

How to prepare

  • Answer aloud and timed: Solve a grid-based prison break problem to find the maximum contiguous open area after removing specific horizontal and vertical grid bars.
  • Answer aloud and timed: Review a provided React component as if conducting a live pull request, identifying performance bottlenecks, unnecessary re-renders, and state management defects.

Where candidates lose points

Practice Code Review out Loud

Since Expedia (IT) includes rounds where you review existing components or code snippets, practice reading code aloud, pointing out performance issues, missing null checks, and state management bugs cleanly.

Structure Behavioral Responses using STAR

Frame every behavioral answer using the Situation, Task, Action, and Result format. Make sure the "Action" segment emphasizes your personal contribution and engineering decisions.

Saying 'eventually consistent' without naming the anomaly a user would see

Describe the concrete symptom you are choosing to accept: the author reloads and their own comment is missing for two seconds, or two devices show different balances for a minute. The class of consistency model is a technical label; the tolerable anomaly is the actual product decision.

Questions & practice

Given a list of meeting or task intervals, merge overlapping intervals and determine the minimum resources req

Medium · Data Structures & Algorithms

Given a list of meeting or task intervals, merge overlapping intervals and determine the minimum resources required to run all tasks concurrently.

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. 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?

Given an array of integers representing maximum tower heights, compute the maximum possible height sum for a v

Medium · Data Structures & Algorithms

Given an array of integers representing maximum tower heights, compute the maximum possible height sum for a valid mountain array configuration.

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Implement a sliding window or binary search strategy to calculate subarray sum limits or find count bounds in

Medium · Data Structures & Algorithms

Implement a sliding window or binary search strategy to calculate subarray sum limits or find count bounds in sorted numerical arrays.

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Given a string containing placeholders or character sequences, generate valid string permutations or count sub

Medium · Data Structures & Algorithms

Given a string containing placeholders or character sequences, generate valid string permutations or count substrings that can be rearranged into palindromes.

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Solve a grid-based prison break problem to find the maximum contiguous open area after removing specific horiz

Medium · Data Structures & Algorithms

Solve a grid-based prison break problem to find the maximum contiguous open area after removing specific horizontal and vertical grid bars.

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Why do you want to join Expedia (IT), and what specific technical domain or product space interests you most?

Medium · Behavioral & Engineering Culture

Approach

  1. Name the grain you start from and join outward from it.
  2. Check whether any join is one-to-many before aggregating, or the sums inflate.
  3. Say which index the query would use, and what makes it unusable.
  4. 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

Medium · window functions · event tables · frame semantics

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

  1. 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.
  2. 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.
  3. 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.
  4. 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?

Review a provided React component as if conducting a live pull request, identifying performance bottlenecks, u

Medium · Code Review, Testing & API Engineering

Review a provided React component as if conducting a live pull request, identifying performance bottlenecks, unnecessary re-renders, and state management defects.

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. 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?

Given an open-ended scenario with a complex raw JSON string, write clean code using standard libraries to pars

Medium · Code Review, Testing & API Engineering

Given an open-ended scenario with a complex raw JSON string, write clean code using standard libraries to parse, validate, and extract target nested fields.

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. 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 how to construct unit tests and integration tests for edge cases in a provided code snippet, explainin

Medium · Code Review, Testing & API Engineering

Discuss how to construct unit tests and integration tests for edge cases in a provided code snippet, explaining proper mock structures and input/output contracts.

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. 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?

Describe the key architectural principles of a REST API, explaining request lifecycle handling, response statu

Medium · Code Review, Testing & API Engineering

Describe the key architectural principles of a REST API, explaining request lifecycle handling, response status codes, and database query optimization strategies.

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. 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?

Design a rate limiter system capable of handling high-frequency API traffic with configurable sliding window t

Medium · System & Low-Level Design

Design a rate limiter system capable of handling high-frequency API traffic with configurable sliding window thresholds.

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. 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?

Create an object-oriented domain design for a user board platform, detailing entity schemas, database relation

Medium · System & Low-Level Design

Create an object-oriented domain design for a user board platform, detailing entity schemas, database relationships, and permission sharing rules.

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Design an automated order cancellation and refund processing system that guarantees transactional consistency

Medium · System & Low-Level Design

Design an automated order cancellation and refund processing system that guarantees transactional consistency and handles downstream failure states.

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Explain how to structure low-level class hierarchies, comparator functions, and specialized collection types l

Medium · System & Low-Level Design

Explain how to structure low-level class hierarchies, comparator functions, and specialized collection types like TreeSet or PriorityQueue to support real-time item rating updates.

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Design an API throttling gateway to handle distributed consumer limits across scalable cloud endpoints.

Medium · System & Low-Level Design

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Explain strategies for troubleshooting and debugging a slow-running microservice in a production cloud context

Medium · Code Review, Testing & API Engineering

Explain strategies for troubleshooting and debugging a slow-running microservice in a production cloud context.

Approach

  1. Establish what changed and when, before forming any theory.
  2. Pick a bisection that eliminates candidates whichever way it turns out.
  3. Check the instrumentation before believing the symptom.
  4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

  • What would you look at first, and what would it rule out?
  • How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics Expedia (IT) candidates report.

Day 1 — Map the Expedia (IT) loop

  • Write out the reported sequence: Initial Screening Assessment, Technical Screening Call, Virtual Evaluation Loop.
  • For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.

Day 2 — Work React

  • Spend the session on React, which Expedia (IT) candidates report being tested on.
  • Write one worked example in React and time yourself on it.

Deliverable: One timed worked example in React.

Day 3 — Work System Design

  • Spend the session on System Design, which Expedia (IT) 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.

Day 4 — Work Code Review (PR Review)

  • Spend the session on Code Review (PR Review), which Expedia (IT) candidates report being tested on.
  • Write one worked example in Code Review (PR Review) and time yourself on it.

Deliverable: One timed worked example in Code Review (PR Review).

Day 5 — Answer out loud: Data Structures & Algorithms

  • Answer aloud, timed: Given a list of meeting or task intervals, merge overlapping intervals and determine the minimum resources required to run all tasks concurrently.
  • Answer aloud, timed: Given an array of integers representing maximum tower heights, compute the maximum possible height sum for a valid mountain array configuration.

Deliverable: Spoken answers to 2 reported Data Structures & Algorithms question(s), under time.

Day 6 — Answer out loud: Code Review, Testing & API Engineering

  • Answer aloud, timed: Review a provided React component as if conducting a live pull request, identifying performance bottlenecks, unnecessary re-renders, and state management defects.
  • Answer aloud, timed: Given an open-ended scenario with a complex raw JSON string, write clean code using standard libraries to parse, validate, and extract target nested fields.

Deliverable: Spoken answers to 2 reported Code Review, Testing & API Engineering question(s), under time.

Day 7 — Answer out loud: System & Low-Level Design

  • Answer aloud, timed: Design a rate limiter system capable of handling high-frequency API traffic with configurable sliding window thresholds.
  • Answer aloud, timed: Create an object-oriented domain design for a user board platform, detailing entity schemas, database relationships, and permission sharing rules.

Deliverable: Spoken answers to 2 reported System & Low-Level Design question(s), under time.

Behavioural preparation

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

Describe a complex or high-impact project you led, focusing on the technical design decisions, implementation

Medium · Behavioral & Engineering Culture

Describe a complex or high-impact project you led, focusing on the technical design decisions, implementation hurdles, and post-launch outcomes.

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

How do you handle situations where you are blocked by a colleague or when team members fail to deliver on agre

Medium · Behavioral & Engineering Culture

How do you handle situations where you are blocked by a colleague or when team members fail to deliver on agreed-upon commitments?

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Share an instance where you had a strong disagreement with a colleague or manager regarding technical directio

Medium · Behavioral & Engineering Culture

Share an instance where you had a strong disagreement with a colleague or manager regarding technical direction, and explain how you reached alignment.

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

How do you leverage modern software tools, including AI development assistants, in your daily coding routine w

Medium · Behavioral & Engineering Culture

How do you leverage modern software tools, including AI development assistants, in your daily coding routine while mitigating code quality or security risks?

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?