# L4
**Role:** Software Engineer · **Level:** Software Engineer
**Company:** [Visa](https://scaleengineer.com/companies/visa)
**Difficulty:** Medium to Hard
**Salary:** US$110000 - US$150000
**Experience:** 4 - 7
**Timeline:** ~14 days
This interview process is for a Software Engineer position at Visa, specifically at the L4 level. It is designed to assess a candidate's technical skills, problem-solving abilities, and cultural fit within the company.
Canonical: https://scaleengineer.com/interviews/visa/software-engineer-software-engineer
---
## Overall evaluation

- Technical Proficiency
- System Design & Architecture
- Behavioral & 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 millions of concurrent users for a social media platform?
- Explain the difference between a process and a thread.
- Describe a time you had to deal with a difficult stakeholder.
- What are the advantages and disadvantages of using microservices?
- How do you ensure data consistency in a distributed system?
- Write a function to reverse a linked list.
- What is the time and space complexity of your solution?
- Tell me about a project you are most proud of.

## Preparation tips

### lists

- Review fundamental data structures and algorithms (arrays, linked lists, trees, graphs, hash maps, sorting, searching).
- 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, databases, message queues).
- Understand common distributed systems concepts (e.g., CAP theorem, consistency models, consensus algorithms).
- Prepare for behavioral questions by reflecting on your past experiences using the STAR method (Situation, Task, Action, Result).
- Research Visa's products, services, and recent news to understand their business context.
- Familiarize yourself with common technologies used at Visa, such as Java, Python, C++, cloud platforms (AWS, Azure), and database technologies (SQL, NoSQL).
- Practice explaining your thought process clearly and concisely, both verbally and in written code.
- 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 core data structures and algorithms. Cover arrays, linked lists, stacks, queues, trees (binary, BST, AVL), heaps, hash tables, and graphs. Practice implementing these and solving problems related to them. Study common sorting and searching algorithms.","shortDescription":"Weeks 1-2: Data Structures & Algorithms fundamentals. Practice implementations and problem-solving."}
- {"title":"System Design","longDescription":"Weeks 3-4: Dive into system design. Learn about designing scalable web applications, databases (SQL vs. NoSQL, sharding, replication), caching strategies, load balancing, message queues, and microservices architecture. Study common design patterns and trade-offs.","shortDescription":"Weeks 3-4: System Design principles. Focus on scalability, databases, caching, and microservices."}
- {"title":"Behavioral Preparation","longDescription":"Week 5: Prepare for behavioral interviews. Reflect on your past projects and experiences. Use the STAR method to structure your answers for common behavioral questions related to teamwork, leadership, problem-solving, and handling challenges.","shortDescription":"Week 5: Behavioral Interview preparation. Use STAR method for common questions."}
- {"title":"Company and Role Research","longDescription":"Week 6: Research Visa and the specific role. Understand Visa's business, products, and values. Review the job description thoroughly and identify key skills and experiences they are looking for. Prepare insightful questions to ask the interviewer.","shortDescription":"Week 6: Company and Role Research. Prepare questions for the interviewer."}

## Location differences

- {"location":"Austin, TX","differences":{"tips":["Familiarize yourself with Visa's core products and services.","Be prepared to discuss your experience with cloud platforms (AWS, Azure, GCP).","Understand common security practices in financial technology.","Practice explaining complex technical concepts clearly and concisely."],"interviewFocus":["Deep understanding of distributed systems and microservices.","Experience with large-scale data processing and real-time analytics.","Knowledge of financial systems and payment processing.","Strong problem-solving and system design skills."],"commonQuestions":["How would you design a system to handle real-time fraud detection for credit card transactions?","Describe a challenging technical problem you faced and how you solved it.","Explain the trade-offs between different database technologies for a high-throughput financial application.","How do you ensure scalability and reliability in a distributed system?","What are your thoughts on microservices architecture for payment processing?"]}}
- {"location":"San Francisco, CA","differences":{"tips":["Highlight projects where you've demonstrated strong coding skills.","Be ready to discuss your experience with Agile methodologies.","Showcase your ability to collaborate and communicate effectively.","Research Visa's technology stack and recent innovations."],"interviewFocus":["Proficiency in backend development and API design.","Experience with cloud-native architectures.","Understanding of data structures and algorithms for performance optimization.","Ability to work with cross-functional teams."],"commonQuestions":["Design an API for a payment gateway that supports multiple currencies.","How would you optimize a database query for a large financial dataset?","Discuss your experience with containerization technologies like Docker and Kubernetes.","What are the key considerations for building a fault-tolerant system?","Explain the principles of RESTful API design."]}}
- {"location":"New York, NY","differences":{"tips":["Prepare examples that demonstrate your adaptability and learning agility.","Be ready to discuss your career goals and how they align with Visa's mission.","Emphasize your contributions to team success.","Understand Visa's commitment to innovation and customer service."],"interviewFocus":["Strong analytical and problem-solving skills.","Experience with machine learning and data science concepts (if applicable to the role).","Ability to adapt to new technologies and challenges.","Understanding of software development lifecycle and best practices."],"commonQuestions":["How would you approach building a scalable recommendation engine for financial products?","Describe a situation where you had to deal with conflicting technical requirements.","What are the challenges of maintaining legacy systems in a financial institution?","Explain the concept of eventual consistency in distributed systems.","How do you stay updated with the latest trends in software engineering?"]}}

## Round 1: Coding and Algorithms
**Type:** Technical Interview (Coding) · **Difficulty:** Medium · **Duration:** 45 min
Coding challenge focusing on data structures and algorithms.
This round focuses on your fundamental programming skills. You will be asked to solve one or two 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 approach to problem-solving. Be prepared to explain your thought process, discuss time and space complexity, and potentially optimize your solution.
**Interviewers look for:** Ability to translate a problem into code.; Understanding of fundamental algorithms and data structures.; Logical thinking and systematic approach to problem-solving.
**Evaluation criteria:** Correctness of the solution.; Efficiency of the algorithm (time and space complexity).; Code clarity and readability.; Problem-solving approach.
**Common rejection reasons:** Inability to articulate thought process.; Incorrect or inefficient algorithm.; Poor coding style or syntax errors.; Lack of understanding of basic data structures.
## Questions

- Given a binary tree, find its inorder traversal.
- Implement a function to find the k-th smallest element in an unsorted array.

## Preparation tips

- Practice coding problems on platforms like LeetCode.
- Understand the time and space complexity of common algorithms.
- Be able to explain your code clearly.
- Think out loud during the interview.

## Round 2: System Design
**Type:** System Design Interview · **Difficulty:** Hard · **Duration:** 60 min
Design a scalable system and discuss trade-offs.
This round assesses your ability to design and architect software systems. You will be given an open-ended problem, such as designing a specific service (e.g., a URL shortener, a social media feed) or a large-scale system. The interviewer will evaluate your understanding of scalability, reliability, availability, and various system components. Be prepared to discuss trade-offs, justify your design choices, and consider potential bottlenecks and failure scenarios.
**Interviewers look for:** Ability to design complex systems from scratch.; Understanding of distributed systems principles.; Experience with trade-offs in system design.; Ability to think about edge cases and failure modes.
**Evaluation criteria:** Scalability of the design.; Reliability and fault tolerance.; Clarity and completeness of the design.; Trade-off analysis.; Understanding of system components (databases, caches, load balancers, etc.).
**Common rejection reasons:** Inability to design a scalable and robust system.; Lack of understanding of distributed systems concepts.; Poor trade-off analysis.; Not considering edge cases or failure scenarios.
## Questions

- Design a system to count unique visitors to a website in real-time.
- Design a distributed cache system.

## Preparation tips

- Study system design concepts and common patterns.
- Practice designing various systems.
- Be prepared to discuss trade-offs.
- Think about scalability, reliability, and maintainability.

## Round 3: Behavioral and Managerial
**Type:** Behavioral Interview · **Difficulty:** Medium · **Duration:** 45 min
Assess behavioral competencies and cultural fit.
This round is typically conducted by the hiring manager and focuses on your behavioral aspects and overall fit with the team and Visa's culture. You will be asked questions about your past experiences, how you handle certain situations, your strengths and weaknesses, and your career goals. Use the STAR method to provide specific and concise examples.
**Interviewers look for:** Teamwork and collaboration skills.; Problem-solving and decision-making abilities.; Adaptability and learning agility.; Alignment with Visa's values.
**Evaluation criteria:** Behavioral competencies (teamwork, leadership, communication).; Cultural fit with Visa.; Motivation and career aspirations.; Past experiences and accomplishments.
**Common rejection reasons:** Lack of alignment with Visa's values.; Poor communication skills.; Inability to provide specific examples.; Negative attitude or lack of enthusiasm.
## Questions

- Tell me about a time you failed and what you learned from it.
- Describe a situation where you had to work with a difficult team member.
- Why are you interested in working at Visa?

## Preparation tips

- Prepare examples using the STAR method.
- Research Visa's values and culture.
- Be ready to discuss your career goals.
- Show enthusiasm for the role and company.