# Software Engineer I
**Role:** Software Engineer · **Level:** L9
**Company:** [Mastercard](https://scaleengineer.com/companies/mastercard)
**Difficulty:** Medium to Hard
**Salary:** US$90000 - US$120000
**Experience:** 1 - 3
**Timeline:** ~14 days
This interview process is for a Software Engineer I (L9) position at Mastercard. It is designed to assess a candidate's technical skills, problem-solving abilities, and cultural fit within the company. The process typically involves multiple rounds, including HR screening, technical interviews focusing on data structures, algorithms, and system design, and a final managerial interview to evaluate leadership potential and team collaboration.
Canonical: https://scaleengineer.com/interviews/mastercard/l9-software-engineer
---
## Overall evaluation

- Technical Aptitude
- Communication and Interpersonal Skills
- Cultural Fit and Motivation

## Questions asked

- Write a function to reverse a linked list.
- Given an array of integers, find the contiguous subarray with the largest sum.
- Design a system to handle real-time stock price updates.
- Tell me about a challenging project you worked on and how you overcame obstacles.
- How would you design a URL shortening service like bit.ly?
- Explain the difference between a process and a thread.
- Describe a situation where you had to disagree with a team member or manager. How did you handle it?
- What are the trade-offs between SQL and NoSQL databases?
- How do you ensure code quality and maintainability?
- What interests you about working at Mastercard?

## Preparation tips

### lists

- Thoroughly review fundamental computer science concepts, including data structures (arrays, linked lists, trees, graphs, hash tables) and algorithms (sorting, searching, dynamic programming, graph traversal).
- Practice coding problems on platforms like LeetCode, HackerRank, or AlgoExpert, focusing on medium to hard difficulty.
- Study system design principles, including scalability, reliability, availability, and common design patterns (e.g., load balancing, caching, database sharding).
- Prepare for behavioral questions using the STAR method (Situation, Task, Action, Result) to showcase your experiences effectively.
- Research Mastercard's products, services, recent news, and company culture to tailor your responses and demonstrate genuine interest.
- Understand the specific technologies and programming languages mentioned in the job description.
- Prepare thoughtful questions to ask the interviewers about the role, team, and company.

### studyPlan

- {"title":"Data Structures and Algorithms Fundamentals","longDescription":"Weeks 1-2: Focus on core data structures (arrays, linked lists, stacks, queues, trees, graphs, hash maps) and their common operations. Practice implementing them from scratch and analyze their time and space complexity. Cover basic algorithms like sorting (quicksort, mergesort) and searching (binary search).","shortDescription":"Weeks 1-2: Data Structures & Basic Algorithms. Implement and analyze common structures. Practice sorting and searching."}
- {"title":"Advanced Algorithms and Problem Solving","longDescription":"Weeks 3-4: Dive deeper into algorithms, including dynamic programming, greedy algorithms, graph algorithms (BFS, DFS, Dijkstra's), and string manipulation. Solve a variety of problems related to these topics on coding platforms.","shortDescription":"Weeks 3-4: Advanced Algorithms. Focus on DP, greedy, graphs, and strings. Solve diverse coding problems."}
- {"title":"System Design Fundamentals","longDescription":"Weeks 5-6: Begin studying system design. Understand concepts like API design, database choices (SQL vs. NoSQL), caching strategies, load balancing, message queues, and microservices architecture. Practice designing common systems like a URL shortener or a social media feed.","shortDescription":"Weeks 5-6: System Design Basics. Learn about scalability, databases, caching, and APIs. Practice designing simple systems."}
- {"title":"Behavioral Interview Preparation","longDescription":"Week 7: Prepare for behavioral interviews. Identify key experiences from your past that demonstrate leadership, teamwork, problem-solving, and handling challenges. Practice articulating these using the STAR method. Research Mastercard's values and prepare examples that align with them.","shortDescription":"Week 7: Behavioral Interview Prep. Use STAR method for past experiences. Align with Mastercard's values."}
- {"title":"Final Review and Practice","longDescription":"Week 8: Consolidate knowledge. Review all topics, focusing on areas where you feel less confident. Conduct mock interviews with peers or mentors to simulate the actual interview environment and get feedback.","shortDescription":"Week 8: Review and Mock Interviews. Consolidate learning. Practice with mock interviews."}

## Location differences

- {"location":"New York","differences":{"tips":["Research Mastercard's presence and recent projects in this specific region.","Be prepared to discuss how your skills align with local business needs.","Highlight any experience working with diverse, international teams."],"interviewFocus":["Adaptability to changing project scopes","Communication and stakeholder management","Understanding of local market challenges and opportunities"],"commonQuestions":["Tell me about a time you had to deal with a difficult stakeholder.","How do you prioritize your work when faced with multiple urgent tasks?","Describe a project where you had to adapt to changing requirements."]}}
- {"location":"London","differences":{"tips":["Brush up on common algorithms and data structures, especially those relevant to financial systems.","Prepare to discuss your experience with large-scale systems and performance optimization.","Familiarize yourself with Mastercard's technology stack and recent innovations."],"interviewFocus":["Deep technical expertise in core programming languages and data structures.","Problem-solving and analytical skills.","Understanding of distributed systems and cloud technologies."],"commonQuestions":["Describe a complex technical problem you solved and your approach.","How do you ensure the scalability and performance of your code?","What are your thoughts on microservices architecture?"]}}
- {"location":"Singapore","differences":{"tips":["Showcase your passion for technology and your drive to learn.","Emphasize your ability to work effectively in a team environment.","Understand Mastercard's mission and how you can contribute to it."],"interviewFocus":["Learning agility and continuous improvement.","Teamwork and collaboration.","Alignment with Mastercard's values and culture."],"commonQuestions":["How do you approach learning a new technology or programming language?","Tell me about a time you failed and what you learned from it.","What are your career aspirations within Mastercard?"]}}

## Round 1: HR Screening Call
**Type:** HR Screening · **Difficulty:** Easy · **Duration:** 30 min
Initial call with HR to discuss your background, interest in Mastercard, and logistics.
The initial HR screening call is conducted by a recruiter to assess your overall fit for the role and the company. They will discuss your resume, career aspirations, salary expectations, and availability. This round also serves to provide you with more information about Mastercard and the specific position.
**Interviewers look for:** Clear communication.; Genuine interest in the role and Mastercard.; Basic understanding of the position's requirements.; Professionalism and positive attitude.
**Evaluation criteria:** Basic understanding of the role and company.; Communication clarity.; Enthusiasm and motivation.; Alignment with basic job requirements.
**Common rejection reasons:** Lack of clarity in communication.; Inability to articulate thought process.; Poor understanding of basic HR policies or company values.
## Questions

- Tell me about yourself and your background.
- Why are you interested in this role at Mastercard?
- What are your salary expectations?
- What are your strengths and weaknesses?

## Preparation tips

- Be prepared to talk about your resume and career goals.
- Research Mastercard's mission, values, and recent news.
- Have a clear understanding of your salary expectations.
- Prepare questions to ask the recruiter about the role and the company culture.

## Round 2: Data Structures and Algorithms Interview
**Type:** Technical Interview (Coding) · **Difficulty:** Medium · **Duration:** 60 min
Solve coding problems focusing on data structures and algorithms.
This technical interview focuses on your fundamental programming skills. You will be asked to solve coding problems, typically involving data structures and algorithms. The interviewer will assess your ability to write clean, efficient, and correct code, as well as your problem-solving approach and ability to explain your thought process.
**Interviewers look for:** Strong grasp of data structures and algorithms.; Ability to translate a problem into working code.; Clear explanation of the solution and its time/space complexity.; Logical and systematic approach to problem-solving.
**Evaluation criteria:** Correctness and efficiency of the code.; Understanding of data structures and algorithms.; Problem-solving approach.; Ability to write clean, readable code.; Explanation of the solution and complexity analysis.
**Common rejection reasons:** Inability to solve coding problems efficiently.; Poor understanding of fundamental data structures and algorithms.; Code contains significant bugs or logical errors.; Difficulty explaining the thought process behind the solution.
## Questions

- Given an array of integers, find the contiguous subarray with the largest sum.
- Implement a function to check if a binary tree is a valid Binary Search Tree (BST).
- Write a function to find the first non-repeating character in a string.
- Reverse a linked list in groups of k.

## Preparation tips

- Practice coding problems on platforms like LeetCode, HackerRank, or AlgoExpert.
- Be prepared to explain your code and analyze its time and space complexity.
- Think out loud and communicate your thought process clearly.
- Ask clarifying questions if the problem statement is unclear.

## Round 3: System Design Interview
**Type:** Technical Interview (System Design) · **Difficulty:** Hard · **Duration:** 60 min
Design a scalable software system based on a given problem statement.
This round assesses your ability to design complex software systems. You'll be presented with a high-level problem (e.g., design Twitter's feed, design a URL shortener) and expected to outline a system architecture. This includes defining APIs, choosing databases, discussing scalability, and considering potential bottlenecks.
**Interviewers look for:** System thinking and architectural design skills.; Understanding of scalability, availability, and performance.; Knowledge of various system components (databases, caches, load balancers, etc.).; Ability to justify design decisions and discuss trade-offs.
**Evaluation criteria:** Ability to design scalable, reliable, and maintainable systems.; Understanding of trade-offs between different design choices.; Knowledge of distributed systems concepts.; Effective communication of design ideas.; Ability to handle ambiguity and make reasoned decisions.
**Common rejection reasons:** Lack of understanding of system design principles.; Inability to design scalable and reliable systems.; Poor trade-off analysis.; Difficulty in handling ambiguity and making design decisions.
## Questions

- Design a URL shortening service like bit.ly.
- Design the backend for a ride-sharing service like Uber.
- How would you design a system to handle millions of concurrent users for a social media platform?
- Design an API for a simple e-commerce product catalog.

## Preparation tips

- Study system design concepts and common patterns.
- Practice designing various systems, considering scalability, reliability, and performance.
- Be prepared to discuss trade-offs and justify your design choices.
- Think about edge cases and potential failure points.

## Round 4: Managerial Interview
**Type:** Managerial / Behavioral Interview · **Difficulty:** Medium · **Duration:** 45 min
Behavioral questions to assess team fit, problem-solving, and career aspirations.
The final round is typically with the hiring manager. This interview focuses on behavioral aspects, your past experiences, and how you would fit into the team and company culture. They will delve deeper into your motivations, career goals, and how you handle various work situations.
**Interviewers look for:** How you handle challenges and collaborate with others.; Your ability to learn and grow.; Your alignment with Mastercard's culture and values.; Your potential to contribute to the team and company long-term.
**Evaluation criteria:** Teamwork and collaboration skills.; Problem-solving approach in real-world scenarios.; Leadership potential.; Adaptability and learning agility.; Alignment with Mastercard's values and culture.; Motivation and career aspirations.
**Common rejection reasons:** Poor cultural fit.; Lack of enthusiasm or motivation.; Inability to articulate past experiences effectively.; Negative attitude towards past employers or colleagues.; Not demonstrating leadership potential or teamwork skills.
## Questions

- Tell me about a time you faced a significant technical challenge and how you overcame it.
- Describe a situation where you had to work with a difficult team member. How did you handle it?
- What are your long-term career goals?
- How do you stay updated with new technologies?
- Why should we hire you for this role?

## Preparation tips

- Prepare examples using the STAR method for common behavioral questions.
- Be ready to discuss your career goals and how this role aligns with them.
- Showcase your understanding of teamwork and collaboration.
- Express genuine enthusiasm for Mastercard and the position.