# Software Engineer
**Role:** Software Engineer · **Level:** MG4
**Company:** [Mercari](https://scaleengineer.com/companies/mercari)
**Difficulty:** Medium to Hard
**Salary:** US$130000 - US$180000
**Experience:** 4 - 8
**Timeline:** ~14 days
Mercari is a leading online marketplace that connects buyers and sellers of new and used goods. This interview process for a Software Engineer at the MG4 level is designed to assess a candidate's technical proficiency, problem-solving skills, and cultural fit within the company.
Canonical: https://scaleengineer.com/interviews/mercari/mg4-software-engineer
---
## Overall evaluation

- Technical Skills
- Communication
- Cultural Fit

## Questions asked

- Given an array of integers, find the contiguous subarray with the largest sum.
- Design a URL shortening service like bit.ly.
- How would you design a system to handle real-time chat messages for a platform like Mercari?
- Tell me about a time you disagreed with a teammate. How did you handle it?
- What are the trade-offs between SQL and NoSQL databases?
- How do you ensure the security of a web application?
- Describe a complex algorithm you've implemented.
- How would you optimize the performance of a slow API endpoint?
- What are your strengths and weaknesses as a software engineer?
- Why are you interested in working at Mercari?

## Preparation tips

### lists

- Thoroughly review data structures and algorithms, focusing on time and space complexity.
- Practice coding problems on platforms like LeetCode, HackerRank, or AlgoExpert.
- Study system design principles and common architectural patterns.
- Prepare to discuss your past projects in detail, highlighting your contributions and the impact you made.
- Understand Mercari's business, products, and values.
- Practice behavioral questions using the STAR method (Situation, Task, Action, Result).
- Prepare questions to ask the interviewer about the role, team, and company culture.

### studyPlan

- {"title":"Data Structures and Algorithms","longDescription":"Weeks 1-2: Focus on fundamental data structures (arrays, linked lists, stacks, queues, trees, graphs, hash tables) and algorithms (sorting, searching, dynamic programming, graph traversal). Practice implementing these and analyzing their complexity. Solve easy to medium LeetCode problems.","shortDescription":"Weeks 1-2: Data Structures & Algorithms fundamentals. Easy/Medium LeetCode."}
- {"title":"System Design","longDescription":"Weeks 3-4: Dive into system design concepts. Study topics like scalability, availability, databases (SQL vs. NoSQL), caching, load balancing, message queues, and microservices. Review common system design interview questions and practice designing systems.","shortDescription":"Weeks 3-4: System Design principles. Scalability, databases, caching."}
- {"title":"Behavioral and Cultural Fit","longDescription":"Week 5: Prepare for behavioral and situational questions. Reflect on your past experiences and prepare examples using the STAR method. Understand Mercari's values and how your experiences align with them.","shortDescription":"Week 5: Behavioral questions (STAR method). Mercari values."}
- {"title":"Mock Interviews and Refinement","longDescription":"Week 6: Mock interviews. Practice with peers or mentors to simulate the interview environment. Get feedback on your technical explanations, problem-solving approach, and communication.","shortDescription":"Week 6: Mock interviews. Practice communication and problem-solving."}

## Location differences

- {"location":"Tokyo, Japan","differences":{"tips":["Familiarize yourself with Mercari's tech stack, particularly if it's cloud-based.","Be prepared to discuss your experience with specific cloud providers and services.","Practice system design questions with a focus on scalability and fault tolerance.","Highlight any experience with CI/CD pipelines and DevOps practices."],"interviewFocus":["Deep understanding of distributed systems and microservices architecture.","Experience with cloud-native technologies (e.g., AWS, Kubernetes).","Ability to design scalable and resilient systems.","Strong problem-solving skills in a cloud environment."],"commonQuestions":["How would you design a system to handle real-time notifications for Mercari's platform?","Describe a time you had to optimize a slow-performing database query. What was your approach?","In a distributed system, how do you ensure data consistency across different services?","Tell me about a challenging bug you encountered and how you debugged it."]}}
- {"location":"Remote (Global)","differences":{"tips":["Review common data structures and algorithms, and practice coding them.","Be ready to discuss your past projects in detail, focusing on your contributions and impact.","Prepare examples that demonstrate your problem-solving abilities and teamwork.","Understand Mercari's business model and how technology supports it."],"interviewFocus":["Strong understanding of data structures and algorithms.","Experience with building and scaling web applications.","Ability to write clean, maintainable, and efficient code.","Good communication and collaboration skills."],"commonQuestions":["How would you design a recommendation engine for Mercari's diverse product catalog?","Describe your experience with A/B testing and how you've used it to improve user experience.","How do you approach performance optimization for a high-traffic web application?","Tell me about a project where you had to collaborate with cross-functional teams (e.g., Product, Design)."]}}

## Round 1: Data Structures and Algorithms
**Type:** Technical Interview (Data Structures & Algorithms) · **Difficulty:** Medium · **Duration:** 45 min
Assess core DSA skills through coding problems.
This round focuses on your core data structures and algorithms knowledge. You will be presented with coding challenges that require you to implement algorithms and data structures efficiently. The interviewer will assess your ability to analyze problems, choose appropriate data structures, write clean code, and explain your thought process.
**Interviewers look for:** A systematic approach to problem-solving.; Proficiency in coding and debugging.; Understanding of algorithmic complexity.; Ability to communicate technical ideas effectively.
**Evaluation criteria:** Correctness of the solution; Efficiency of the solution (time and space complexity); Code clarity and readability; Ability to handle edge cases; Problem-solving approach
**Common rejection reasons:** Inability to articulate thought process clearly.; Poor understanding of fundamental data structures and algorithms.; Difficulty in solving coding problems within the given time.; Lack of attention to edge cases and constraints.
## Questions

- Given a binary tree, invert the tree.
- Find the kth largest element in an unsorted array.
- Implement a function to check if a string is a palindrome.

## Preparation tips

- Practice coding problems on platforms like LeetCode, focusing on common patterns.
- Understand the time and space complexity of your solutions.
- Be prepared to explain your approach and trade-offs.
- Practice writing code on a whiteboard or in a shared editor.

## Round 2: System Design
**Type:** System Design Interview · **Difficulty:** Hard · **Duration:** 60 min
Assess system design capabilities for scalable applications.
This round evaluates your ability to design scalable, reliable, and maintainable software systems. You'll be asked to design a system based on a given problem statement, considering aspects like architecture, data storage, APIs, and performance. The focus is on your ability to think through complex problems and make sound engineering decisions.
**Interviewers look for:** Ability to design complex systems from scratch.; Understanding of distributed systems principles.; Experience with various architectural patterns.; Pragmatic approach to problem-solving and trade-offs.
**Evaluation criteria:** Scalability of the design; Availability and reliability; System performance; Choice of technologies and architectural patterns; Handling of edge cases and failure modes; Trade-off analysis
**Common rejection reasons:** Inability to design scalable and robust systems.; Lack of understanding of distributed system concepts.; Poor consideration of trade-offs and failure scenarios.; Difficulty in explaining design choices.
## Questions

- Design a system to shorten URLs.
- Design a news feed system for a social media platform.
- Design a rate limiter.

## Preparation tips

- Study common system design patterns (e.g., microservices, event-driven architecture).
- Understand concepts like load balancing, caching, database sharding, and message queues.
- Practice designing systems like social media feeds, e-commerce platforms, or real-time services.
- Be prepared to discuss trade-offs and justify your design choices.

## Round 3: Behavioral and Managerial Fit
**Type:** Behavioral and Managerial Interview · **Difficulty:** Medium · **Duration:** 45 min
Assess behavioral competencies and cultural fit.
This round focuses on your behavioral and cultural fit. You'll be asked questions about your past experiences, how you handle different situations, and your motivations. The interviewer wants to understand how you work with others, your problem-solving approach in real-world scenarios, and whether you align with Mercari's values.
**Interviewers look for:** Evidence of collaboration and teamwork.; Ability to handle challenging situations and conflicts.; Proactiveness and ownership.; Cultural fit and alignment with Mercari's principles.
**Evaluation criteria:** Behavioral competencies (teamwork, communication, problem-solving); Alignment with Mercari's culture and values; Motivation and passion for the role and company; Past experiences and achievements
**Common rejection reasons:** Poor communication and interpersonal skills.; Lack of alignment with company values.; Inability to provide specific examples of past experiences.; Negative attitude or lack of enthusiasm.
## 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 colleague. How did you manage the relationship?
- Why are you interested in Mercari?

## Preparation tips

- Prepare examples using the STAR method for common behavioral questions.
- Research Mercari's company culture and values.
- Be ready to discuss your career goals and why you're interested in this role.
- Show enthusiasm and genuine interest in the company.