Hopper Software Engineer Interview Questions + Guide in 2025

Hopper is on a mission to revolutionize the travel industry by leveraging data and machine learning to create a seamless booking experience for millions of travelers.

As a Software Engineer at Hopper, you will play a pivotal role in designing, building, and maintaining scalable backend systems that directly impact user experiences. Your responsibilities will include collaborating with cross-functional teams, conducting code reviews, and developing high-quality APIs and features. The ideal candidate will possess a strong foundation in backend development, particularly in Scala or similar JVM languages, and have experience in operating distributed systems within cloud environments, specifically Google Cloud Platform (GCP). You will thrive in a fast-paced, agile environment and be passionate about delivering results quickly while maintaining high code quality.

This guide will help you prepare for your interview by providing insights into the expectations and culture at Hopper, enabling you to effectively showcase your skills and align your experiences with their values.

In this section, we’ll review the various interview questions that might be asked during a software engineering interview at Hopper. The interview process will likely focus on your technical skills, problem-solving abilities, and cultural fit within the company. Be prepared to discuss your experience with distributed systems, coding challenges, and your approach to software development.

Technical Skills

1. Can you explain the differences between REST and gRPC?

Understanding the communication methods used in microservices is crucial for this role.

How to Answer

Discuss the key differences in terms of performance, data format, and use cases. Highlight your experience with both if applicable.

Example

"REST is an architectural style that uses standard HTTP methods and is typically easier to use and understand. In contrast, gRPC is a high-performance RPC framework that uses Protocol Buffers for serialization, making it faster and more efficient for service-to-service communication, especially in microservices architectures."

2. Describe a challenging project you worked on involving distributed systems.

This question assesses your experience with complex systems.

How to Answer

Focus on the project’s goals, your role, the challenges faced, and how you overcame them.

Example

"I worked on a distributed booking system where we had to ensure data consistency across multiple services. We implemented a saga pattern to manage transactions, which allowed us to maintain data integrity while providing a seamless user experience."

3. How do you ensure the quality of your code?

Quality assurance is vital in software development.

How to Answer

Discuss your practices for code reviews, testing, and adherence to coding standards.

Example

"I prioritize writing unit tests and conducting thorough code reviews. I also use static analysis tools to catch potential issues early and ensure that my code adheres to best practices."

4. Can you walk me through your approach to debugging a complex issue?

Debugging skills are essential for a software engineer.

How to Answer

Outline your systematic approach to identifying and resolving issues.

Example

"When debugging, I first reproduce the issue and gather as much information as possible. I then isolate the problem by checking logs and using debugging tools to trace the execution flow, allowing me to pinpoint the root cause effectively."

5. What is your experience with cloud services, particularly GCP?

Familiarity with cloud platforms is important for this role.

How to Answer

Share your experience with GCP services and how you’ve utilized them in past projects.

Example

"I have experience deploying applications on GCP using services like Google Kubernetes Engine for orchestration and BigQuery for data analysis. I appreciate GCP's scalability and the ease of integrating various services."

Behavioral Questions

1. Tell me about a time you had to work with a difficult team member.

This question evaluates your interpersonal skills and conflict resolution abilities.

How to Answer

Describe the situation, your approach to resolving the conflict, and the outcome.

Example

"I once worked with a team member who was resistant to feedback. I scheduled a one-on-one meeting to discuss our differences openly, which helped us understand each other's perspectives and ultimately improved our collaboration."

2. How do you prioritize your tasks when working on multiple projects?

Time management is crucial in a fast-paced environment.

How to Answer

Explain your method for prioritizing tasks and managing deadlines.

Example

"I use a combination of Agile methodologies and tools like Trello to prioritize tasks based on urgency and impact. I also communicate regularly with my team to ensure alignment on project goals."

3. Describe a time when you had to learn a new technology quickly.

Adaptability is key in the tech industry.

How to Answer

Share the context, your learning process, and how you applied the new technology.

Example

"When our team decided to migrate to Scala, I dedicated time to online courses and hands-on practice. Within a few weeks, I was able to contribute to our codebase and help onboard other team members."

4. What motivates you to work in the travel technology industry?

Understanding your passion for the industry can help assess cultural fit.

How to Answer

Discuss your interest in travel and technology, and how they intersect.

Example

"I've always been passionate about travel and technology. Working in travel tech allows me to combine these interests and contribute to solutions that enhance people's travel experiences."

5. How would you describe your ideal work environment?

This question helps gauge if you align with Hopper's culture.

How to Answer

Share your preferences for collaboration, autonomy, and company values.

Example

"I thrive in a collaborative environment where open communication is encouraged. I appreciate a culture that values innovation and allows for experimentation, which I believe aligns well with Hopper's entrepreneurial spirit."

Here are some tips to help you excel in your interview.

Understand the Interview Process

Familiarize yourself with Hopper's interview structure, which typically includes a technical assessment followed by multiple rounds of interviews. Expect a mix of coding challenges, system design questions, and behavioral interviews. Knowing the format will help you prepare effectively and manage your time during the interviews.

Master the Technical Skills

Given that Hopper's tech stack includes Scala, GCP, and various database technologies, ensure you are comfortable with these tools. Brush up on your knowledge of distributed systems, APIs, and microservices architecture. Practice coding problems on platforms like LeetCode or HackerRank, focusing on data structures and algorithms, as many candidates report that these are common topics in interviews.

Prepare for Behavioral Questions

Hopper values candidates who can articulate their experiences and thought processes clearly. Use the STAR (Situation, Task, Action, Result) method to structure your responses to behavioral questions. Be ready to discuss your past projects, how you overcame challenges, and how you contributed to team success. Highlight your ability to work in a fast-paced, collaborative environment, as this aligns with Hopper's culture.

Showcase Your Problem-Solving Skills

During technical interviews, interviewers will be looking for your problem-solving approach as much as the final solution. Think aloud while coding to demonstrate your thought process. If you encounter a challenge, don't hesitate to ask clarifying questions or discuss alternative approaches. This shows your ability to collaborate and adapt, which is crucial in a dynamic environment like Hopper.

Emphasize Cultural Fit

Hopper has a strong entrepreneurial culture that encourages innovation and risk-taking. Research the company's values and be prepared to discuss how your personal values align with theirs. Show enthusiasm for the travel industry and how you can contribute to Hopper's mission of transforming travel technology.

Communicate Effectively

Effective communication is key, especially in a remote interview setting. Ensure you have a stable internet connection and a quiet environment for your interviews. Practice articulating your thoughts clearly and concisely, as many candidates have noted that interviewers appreciate candidates who can communicate well.

Follow Up

After your interviews, consider sending a thank-you email to express your appreciation for the opportunity to interview. This not only shows professionalism but also reinforces your interest in the position. If you receive feedback, be open to it and use it as a learning opportunity for future interviews.

By following these tips, you can position yourself as a strong candidate for the Software Engineer role at Hopper. Good luck!

The interview process for a Software Engineer at Hopper is structured to assess both technical skills and cultural fit within the company. It typically consists of several stages, each designed to evaluate different aspects of a candidate's qualifications and compatibility with Hopper's values.

1. Initial Screening

The process begins with an initial screening call, usually conducted by a recruiter. This conversation lasts about 30-45 minutes and focuses on your background, experience, and motivation for applying to Hopper. The recruiter will also provide insights into the company culture and the specifics of the role, ensuring that you have a clear understanding of what to expect.

2. Technical Assessment

Following the initial screening, candidates are required to complete a technical assessment, often hosted on platforms like HackerRank. This assessment typically lasts around 1-2 hours and includes coding challenges that test your problem-solving abilities and familiarity with data structures and algorithms. The questions are generally aligned with LeetCode-style problems, so familiarity with that format can be beneficial.

3. Technical Interview

If you perform well on the technical assessment, the next step is a technical interview, which is usually conducted via video call. This interview lasts about an hour and involves live coding exercises. You will be asked to solve problems in real-time while explaining your thought process to the interviewer. Expect questions that require you to demonstrate your understanding of algorithms, system design, and possibly some aspects of the tech stack used at Hopper, such as Scala and GCP.

4. Onsite Interviews

Candidates who successfully navigate the technical interview may be invited for onsite interviews, which can be conducted virtually as well. This stage typically consists of multiple rounds (often 3-5), each lasting about an hour. These interviews will include a mix of technical questions, system design discussions, and behavioral questions. Interviewers may assess your ability to work collaboratively, your approach to problem-solving, and how you align with Hopper's values.

5. Final Interview

The final stage often includes a "bar raiser" interview, which is designed to ensure that candidates meet the high standards expected at Hopper. This interview may focus on behavioral questions and cultural fit, assessing how well you would integrate into the team and contribute to the company's mission.

Throughout the process, candidates are encouraged to ask questions and engage with interviewers to better understand the role and the company culture.

As you prepare for your interviews, consider the types of questions that may arise in each stage, particularly those that align with Hopper's focus on customer-centric solutions and innovative problem-solving.

1. How would you improve the search feature for activities in San Francisco on the Facebook app?

We want to enhance the search results for users looking for things to do in San Francisco. What would you investigate, and what metrics would you use to evaluate the current search functionality’s performance?

2. What’s the difference between Lasso and Ridge Regression?

Explain the key differences between Lasso and Ridge Regression, focusing on their regularization techniques and how they handle coefficients.

3. What kind of model did the co-worker develop for loan approval?

Your co-worker developed a model that takes customer inputs to decide loan approval. Identify the type of model used.

4. How would you compare two credit risk models for predicting loan defaults? What metrics would you track to measure the success of a new credit risk model?

Since personal loans are monthly installments, describe how you would measure the difference between the two credit risk models over time.

Identify the key metrics you would use to evaluate the success of a new model predicting loan defaults.

5. How would you evaluate if a decision tree is the correct model for predicting loan repayment? How would you evaluate its performance before and after deployment?

Describe the criteria and methods you would use to determine if a decision tree algorithm is suitable for predicting loan repayment.

Explain the steps and metrics you would use to assess its performance before and after deployment.

6. How does random forest generate the forest and why use it over logistic regression?

Describe the process by which a random forest generates its forest and explain the advantages of using it over logistic regression.

7. How would you interpret coefficients of logistic regression for categorical and boolean variables?

Explain the interpretation of logistic regression coefficients when dealing with categorical and boolean variables.

8. What is the expected number of good ads rated by different types of raters?

1. Suppose we have 100 raters, each rating one ad independently. What’s the expected number of good ads?
2. Now, suppose we have 1 rater rating 100 ads. What’s the expected number of good ads?
3. Suppose we have 1 ad rated as bad. What’s the probability the rater was lazy?

9. How would you simulate coin tosses with a given probability of heads?

Write a function that takes the number of tosses and the probability of heads as input and returns a list of randomly generated results (‘H’ for heads, ’T’ for tails) equal in length to the number of tosses.

10. How would you calculate the sample variance of a list of integers?

Write a function that inputs a list of integers and outputs the sample variance, rounded to 2 decimal places.

11. What is the probability of rolling at least one 3 with dice?

1. What’s the probability of rolling at least one 3 with 2 dice?
2. What’s the probability of rolling at least one 3 given (N) dice?

12. What is the probability of finding an item on Amazon’s website given its availability in warehouses?

Given that the probability of item X being available at warehouse A is 0.6 and at warehouse B is 0.8, what is the probability that item X would be found on Amazon’s website?

13. Create a function find_bigrams to return a list of all bigrams in a sentence.

Write a function called find_bigrams that takes a sentence or paragraph of strings and returns a list of all its bigrams in order. A bigram is a pair of consecutive words.

14. Write a query to get the last transaction for each day from a table of bank transactions.

Given a table of bank transactions with columns id, transaction_value, and created_at, write a query to get the last transaction for each day. The output should include the id, datetime, and transaction amount, ordered by datetime.

15. Create a function find_change to find the minimum number of coins for a given amount.

Write a function find_change to find the minimum number of coins that make up the given amount of change cents. Assume we only have coins of value 1, 5, 10, and 25 cents.

16. Design a function to simulate drawing balls from a jar.

Write a function to simulate drawing balls from a jar. The colors of the balls are stored in a list named jar, with corresponding counts of the balls stored in the same index in a list called n_balls.

17. Develop a function calculate_rmse to compute the root mean squared error.

Write a function calculate_rmse to calculate a regression model’s root mean squared error. The function should take in two lists, one representing the predictions y_pred and another with the target values y_true.

Here are some tips on how you can effectively prepare for a Hopper software engineer interview:

1. Know Your CS Fundamentals: Hopper interview questions are standardized and heavily focused on data structures and algorithms. Study and practice problems on Interview Query to strengthen these areas.

2. Understand System Design Basics: Be prepared for a system design round where you must demonstrate your ability to craft scalable and efficient systems. Practice designing real-world solutions that consider trade-offs and optimizations.

3. Showcase Cultural Fit: Hopper values innovation, customer obsession, and leadership qualities. Prepare to discuss experiences and scenarios where you exhibited these traits.

What is the average salary for a Software Engineer at Hopper?

What skills are vital for a software engineer at Hopper?

Key skills include strong backend development, proficiency in Scala or other JVM languages, experience with cloud platforms like Google Cloud, and an understanding of system architecture. Familiarity with service communication methods and infrastructure deployment tools like Terraform is also important.

What is the company culture like at Hopper?

Hopper promotes a culture of entrepreneurship, open communication, and risk-taking. The company values pushing limits and innovation, focusing on customer satisfaction and system quality. Employees enjoy unlimited PTO, a work-from-home stipend, and engaging in team activities.

Interviewing for a Software Engineer position at Hopper can be a multifaceted experience. It is characterized by a series of technical challenges and interactions that test a candidate’s coding, design, and behavioral skills.

For those eager to excel, Interview Query is an invaluable resource. It offers insights and practice questions tailored to Hopper’s interview process. Whether preparing for a software engineering role or for another position at Hopper, this guide will equip you with the necessary tools to navigate the challenges and make a strong impression.

Good luck with your interview!