Chartboost Software Engineer Interview Questions + Guide in 2025

Chartboost is a leading in-app monetization and programmatic advertising platform that connects mobile app developers with a global audience of over 700 million monthly active users.

As a Software Engineer at Chartboost, you will be at the forefront of developing high-performance systems that handle real-time bidding and advertising auctions. Your responsibilities will include designing and implementing core components of the platform, ensuring low latency and high throughput for processing potentially hundreds of thousands of requests per second. You will collaborate with cross-functional teams, including product managers and system architects, to enhance system features and resolve issues. A strong focus on clean code, unit testing, and mentoring junior engineers will be key aspects of your role. Candidates should possess a solid foundation in algorithms, problem-solving skills, and experience with various programming languages, with an emphasis on developing low-latency applications.

This guide will help you prepare for your interview by providing insights into the expectations and challenges you may face in this role, as well as the skills that will set you apart from other candidates.

The interview process for a Software Engineer at Chartboost is designed to assess both technical skills and cultural fit within the team. It typically consists of several stages, each focusing on different aspects of the candidate's abilities and experiences.

1. Initial Screening

The process begins with an initial screening, which is usually a phone interview with a recruiter or the hiring manager. This conversation lasts about 30-45 minutes and serves to discuss the candidate's background, motivations, and understanding of the role. The recruiter will also provide insights into Chartboost's culture and the expectations for the position.

2. Technical Assessment

Following the initial screening, candidates are often required to complete a technical assessment. This may take the form of a coding challenge or a take-home project that tests the candidate's problem-solving skills and proficiency in relevant programming languages. The assessment typically has a time limit, allowing candidates to demonstrate their ability to work under pressure while showcasing their coding style and approach to algorithm development.

3. Virtual Onsite Interviews

Candidates who perform well in the technical assessment are invited to participate in a virtual onsite interview. This stage usually consists of multiple rounds, often four, where candidates meet with various team members, including engineers and managers. Each interview focuses on different areas, such as system design, algorithms, and behavioral questions. Candidates should be prepared to discuss their past experiences, technical challenges they have faced, and how they approach collaboration and mentorship within a team.

4. Final Interview

The final interview may involve discussions with senior leadership or cross-functional team members. This round assesses the candidate's alignment with Chartboost's values and their potential impact on the organization. Candidates may be asked to present their previous work or discuss how they would approach specific challenges relevant to the role.

Throughout the interview process, candidates should be ready to demonstrate their understanding of high-performance, low-latency applications, as well as their ability to work effectively in an Agile environment.

Next, let's explore the specific interview questions that candidates have encountered during this process.

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

Understand the Interview Structure

Chartboost's interview process typically consists of multiple rounds, including an initial screening with HR, a coding interview, and a virtual on-site with several technical interviews. Familiarize yourself with this structure and prepare accordingly. Expect to demonstrate your problem-solving skills and technical knowledge, particularly in algorithms and system design.

Showcase Your Problem-Solving Skills

Given the emphasis on algorithms and performance, be prepared to tackle complex coding challenges. Practice solving algorithmic problems on platforms like LeetCode or HackerRank, focusing on efficiency and optimization. During the interview, articulate your thought process clearly, explaining your reasoning and the trade-offs of your chosen solutions.

Prepare for Behavioral Questions

Chartboost values collaboration and communication, so expect behavioral questions that assess your teamwork and problem-solving abilities. Use the STAR (Situation, Task, Action, Result) method to structure your responses, highlighting specific examples from your past experiences that demonstrate your ability to work effectively in a team and handle challenges.

Emphasize Clean Code and Best Practices

As a software engineer at Chartboost, you will be expected to write clean, maintainable code. Be prepared to discuss your coding standards and practices, including how you approach unit testing and code reviews. Demonstrating a commitment to code quality will resonate well with your interviewers.

Familiarize Yourself with Relevant Technologies

While the role may not require deep expertise in every technology listed, having a solid understanding of the tools and languages relevant to Chartboost's tech stack—such as Python, Golang, and cloud infrastructure (AWS or GCP)—will be beneficial. Be ready to discuss your experience with these technologies and how they relate to the role.

Engage with Your Interviewers

During the interview, take the opportunity to engage with your interviewers. Ask insightful questions about the team, projects, and company culture. This not only shows your interest in the role but also helps you assess if Chartboost is the right fit for you.

Reflect the Company Culture

Chartboost values innovation, collaboration, and a growth mindset. Be sure to convey your enthusiasm for learning and trying new things. Share examples of how you've embraced challenges and contributed to team success in previous roles. This alignment with the company culture can set you apart from other candidates.

Follow Up Thoughtfully

After your interview, send a thoughtful thank-you email to your interviewers. Express your appreciation for the opportunity to interview and reiterate your interest in the role. This small gesture can leave a positive impression and reinforce your enthusiasm for joining the Chartboost team.

By following these tips and preparing thoroughly, you'll position yourself as a strong candidate for the Software Engineer role at Chartboost. Good luck!

In this section, we’ll review the various interview questions that might be asked during a Software Engineer interview at Chartboost. The interview process will likely focus on your technical skills, problem-solving abilities, and your experience with high-performance, low-latency applications. Be prepared to discuss algorithms, coding practices, and your approach to collaboration and troubleshooting.

Algorithms and Problem Solving

1. How would you approach optimizing a database query?

This question assesses your understanding of database performance and optimization techniques.

How to Answer

Discuss specific strategies you would use to analyze and improve query performance, such as indexing, query rewriting, or analyzing execution plans.

Example

"I would start by examining the query execution plan to identify bottlenecks. If I find that certain columns are frequently queried, I would consider adding indexes. Additionally, I would look for opportunities to rewrite the query to reduce complexity and improve efficiency."

2. Can you explain Big O notation and its importance?

This question tests your knowledge of algorithm efficiency and complexity.

How to Answer

Explain what Big O notation is and why it is crucial for evaluating the performance of algorithms, especially in high-load systems.

Example

"Big O notation describes the upper limit of an algorithm's running time as the input size grows. It's essential for understanding how an algorithm will perform under load, which is critical in a high-performance environment like Chartboost."

3. Describe a time when you had to debug a complex issue in a production system.

This question evaluates your troubleshooting skills and experience with real-world applications.

How to Answer

Share a specific example, detailing the steps you took to identify and resolve the issue, and what you learned from the experience.

Example

"In a previous role, we experienced a significant slowdown in our application. I used logging and monitoring tools to trace the issue back to a poorly optimized query. After rewriting the query and adding appropriate indexes, we saw a 50% improvement in performance."

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

This question assesses your commitment to best practices in software development.

How to Answer

Discuss your approach to writing clean code, including practices like code reviews, unit testing, and continuous integration.

Example

"I prioritize writing clean, maintainable code by following established coding standards and conducting regular code reviews. I also implement unit tests to ensure that my code behaves as expected and integrates well with the overall system."

5. What strategies do you use for effective collaboration with cross-functional teams?

This question gauges your teamwork and communication skills.

How to Answer

Explain how you approach collaboration, including tools and methods you use to communicate effectively with team members from different disciplines.

Example

"I use tools like Slack and Jira to maintain open lines of communication with my team. I also schedule regular check-ins to discuss progress and address any blockers, ensuring that everyone is aligned on project goals."

Technical Skills

1. What programming languages are you most comfortable with, and why?

This question assesses your technical proficiency and preferences.

How to Answer

Mention the languages you are proficient in, particularly those relevant to the role, and explain why you prefer them.

Example

"I am most comfortable with Python and Scala. I appreciate Python for its readability and extensive libraries, while Scala's functional programming features allow me to write concise and efficient code, especially for distributed systems."

2. How do you handle version control in your projects?

This question evaluates your experience with version control systems.

How to Answer

Discuss your familiarity with version control tools, your branching strategies, and how you manage code changes.

Example

"I use Git for version control, following a branching strategy that includes feature branches for new developments and a main branch for stable releases. This approach allows for parallel development while maintaining code integrity."

3. Can you explain the concept of microservices and their advantages?

This question tests your understanding of modern software architecture.

How to Answer

Define microservices and discuss their benefits, particularly in terms of scalability and maintainability.

Example

"Microservices are an architectural style that structures an application as a collection of loosely coupled services. This approach allows for independent deployment, scaling, and development, which enhances the overall agility and resilience of the system."

4. Describe your experience with cloud infrastructure management.

This question assesses your familiarity with cloud services and infrastructure.

How to Answer

Share your experience with specific cloud platforms and how you've utilized them in past projects.

Example

"I have experience managing applications on AWS, where I utilized services like EC2 for compute resources and S3 for storage. I also implemented auto-scaling to handle varying loads efficiently."

5. How do you approach learning new technologies?

This question evaluates your commitment to continuous learning and adaptability.

How to Answer

Discuss your strategies for staying updated with new technologies and how you integrate them into your work.

Example

"I regularly follow tech blogs and participate in online courses to learn about new technologies. I also enjoy experimenting with new tools in personal projects to understand their practical applications before introducing them to my team."