# Software Engineer
**Role:** Software Engineer · **Level:** L5
**Company:** [Twitch](https://scaleengineer.com/companies/twitch)
**Difficulty:** Hard
**Salary:** US$150000 - US$200000
**Experience:** 5 - 10
**Timeline:** ~14 days
This interview process is for a Software Engineer (L5) role at Twitch. It is designed to assess a candidate's technical skills, problem-solving abilities, system design knowledge, and cultural fit within the company.
Canonical: https://scaleengineer.com/interviews/twitch/l5-software-engineer
---
## Overall evaluation

- Technical Skills
- System Design
- Behavioral and Cultural Fit

## Questions asked

- Design a system to handle live streaming for millions of concurrent users.
- How would you optimize the performance of a real-time chat application?
- Describe a complex technical problem you solved and your approach.
- Tell me about a time you disagreed with a technical decision and how you handled it.
- What are the trade-offs between monolithic and microservices architectures?
- How do you ensure the scalability and reliability of a distributed system?
- Explain the CAP theorem and its implications for distributed systems.
- How would you design a recommendation engine for Twitch content?
- Describe your experience with mentoring junior engineers.
- What are your thoughts on the future of live streaming technology?

## Preparation tips

### lists

- Review fundamental data structures and algorithms.
- Practice system design problems, focusing on scalability, reliability, and trade-offs.
- Prepare to discuss your past projects in detail, highlighting your contributions and challenges.
- Understand Twitch's products, services, and technical challenges.
- Brush up on behavioral interview techniques and prepare STAR method examples.
- Research common interview questions for L5 Software Engineers at tech companies.

### studyPlan

- {"title":"Data Structures and Algorithms","longDescription":"Weeks 1-2: Focus on Data Structures and Algorithms. Cover arrays, linked lists, trees, graphs, hash tables, sorting, searching, dynamic programming, and greedy algorithms. Practice problems on platforms like LeetCode, HackerRank, and AlgoExpert. Aim for at least 2-3 problems per day.","shortDescription":"Weeks 1-2: DSA fundamentals. Practice 2-3 problems daily."}
- {"title":"System Design","longDescription":"Weeks 3-4: Dive into System Design. Study concepts like load balancing, caching, databases (SQL vs. NoSQL), message queues, microservices, API design, and distributed systems. Read system design primers and practice designing common systems like Twitter feed, URL shortener, or a chat application.","shortDescription":"Weeks 3-4: System Design concepts. Practice designing common systems."}
- {"title":"Behavioral Preparation","longDescription":"Week 5: Behavioral and Behavioral System Design. Prepare for common behavioral questions using the STAR method. Think about your past experiences related to teamwork, leadership, problem-solving, and handling failure. Also, prepare for behavioral aspects of system design, such as how you'd handle team disagreements on design choices.","shortDescription":"Week 5: Behavioral prep using STAR. Practice behavioral system design."}
- {"title":"Final Preparation","longDescription":"Week 6: Company Research and Mock Interviews. Research Twitch's culture, values, and recent news. Understand their products and how they operate. Conduct mock interviews with peers or mentors to simulate the actual interview environment and get feedback.","shortDescription":"Week 6: Twitch research and mock interviews."}

## Location differences

- {"location":"San Francisco","differences":{"tips":["Be prepared to discuss specific examples of large-scale systems you've worked on.","Emphasize your contributions to system design and architecture.","Showcase your ability to mentor and guide other engineers.","Research Twitch's technical challenges and be ready to discuss potential solutions."],"interviewFocus":["Deep understanding of distributed systems and scalability.","Experience with high-throughput, low-latency systems.","Strong problem-solving and debugging skills.","Ability to lead and mentor technical teams."],"commonQuestions":["How would you design a real-time notification system for Twitch?","Discuss a challenging debugging scenario you faced and how you resolved it.","Describe your experience with large-scale distributed systems.","How do you approach performance optimization in a web application?","Tell me about a time you had to mentor junior engineers."]}}
- {"location":"Seattle","differences":{"tips":["Highlight your experience with cloud platforms and services.","Be ready to discuss your approach to building and deploying scalable applications.","Demonstrate your ability to adapt to new technologies and learn quickly.","Understand Twitch's business model and how technology supports it."],"interviewFocus":["Proficiency in cloud computing and microservices architecture.","Experience with data processing and analytics at scale.","Strong understanding of software development best practices.","Adaptability and continuous learning."],"commonQuestions":["Design a system to handle live chat for millions of concurrent users.","How would you optimize database queries for a rapidly growing user base?","Discuss your experience with cloud-native architectures (e.g., AWS, Azure, GCP).","Tell me about a project where you had to make significant trade-offs in system design.","How do you stay updated with the latest technologies and trends?"]}}

## Round 1: Technical Screen - Coding
**Type:** Data Structures and Algorithms Interview · **Difficulty:** Medium · **Duration:** 45 min
Coding problems focused on DSA.
This round focuses on fundamental data structures and algorithms. You will be asked to solve coding problems on a whiteboard or shared editor. The interviewer will assess your ability to analyze problems, choose appropriate data structures and algorithms, write efficient code, and explain your reasoning.
**Interviewers look for:** Strong understanding of core computer science concepts.; Ability to write clean, efficient, and bug-free code.; Logical thinking and problem-solving skills.; Clear communication of approach.
**Evaluation criteria:** Correctness of code.; Efficiency of algorithms and data structures.; Code clarity and readability.; Problem-solving approach.; Communication of thought process.
**Common rejection reasons:** Lack of fundamental programming knowledge.; Inability to solve basic algorithmic problems.; Poor coding practices.; Difficulty in explaining thought process.
## Questions

- Given an array of integers, find the contiguous subarray with the largest sum.
- Implement a function to reverse a linked list.
- Find the kth smallest element in a binary search tree.

## Preparation tips

- Practice coding problems on platforms like LeetCode, HackerRank.
- Focus on time and space complexity analysis.
- Be prepared to explain your solution and discuss alternative approaches.
- Practice coding without an IDE to simulate interview conditions.

## Round 2: System Design
**Type:** System Design Interview · **Difficulty:** Hard · **Duration:** 60 min
Design a scalable system.
This round assesses your ability to design complex, scalable systems. You will be given an open-ended problem (e.g., design a system like Twitter, YouTube, or a chat application) and expected to propose a high-level architecture, discuss components, data flow, and trade-offs. Focus on scalability, reliability, and performance.
**Interviewers look for:** Experience in designing large-scale, distributed systems.; Knowledge of system design principles (e.g., load balancing, caching, databases).; Ability to articulate design choices and justify trade-offs.; Consideration of non-functional requirements (performance, availability, etc.).
**Evaluation criteria:** Scalability of the proposed design.; Reliability and fault tolerance.; Understanding of trade-offs.; Clarity and completeness of the design.; Ability to handle edge cases and constraints.
**Common rejection reasons:** Inability to design scalable systems.; Lack of understanding of distributed system concepts.; Poor trade-off analysis.; Not considering edge cases or failure scenarios.
## Questions

- Design a URL shortening service like bit.ly.
- Design a real-time analytics dashboard for Twitch.
- Design a distributed cache system.

## Preparation tips

- Study common system design patterns and concepts.
- Practice designing various systems, considering different constraints.
- Be prepared to discuss your design choices and justify trade-offs.
- Think about potential bottlenecks and failure points.

## Round 3: Behavioral and Managerial Interview
**Type:** Behavioral Interview · **Difficulty:** Medium · **Duration:** 45 min
Behavioral questions and cultural fit.
This round focuses on your past experiences, behavioral competencies, and cultural fit. You'll be asked questions about your career, how you handle specific situations (e.g., conflict, failure, success), and your motivations for joining Twitch. Prepare to share specific examples using the STAR method.
**Interviewers look for:** Ability to work effectively in a team.; Examples of leadership and initiative.; How candidates handle challenges and conflicts.; Passion for Twitch and its mission.; Self-awareness and learning agility.
**Evaluation criteria:** Communication clarity.; Teamwork and collaboration.; Problem-solving approach in past projects.; Leadership potential.; Cultural fit and alignment with Twitch values.
**Common rejection reasons:** Poor communication skills.; Lack of collaboration or teamwork.; Inability to articulate past experiences.; Not aligning with company values.; Lack of enthusiasm or motivation.
## Questions

- Tell me about a time you had to work with a difficult colleague.
- Describe a project you are particularly proud of and your role in it.
- How do you handle constructive criticism?

## Preparation tips

- Prepare examples for common behavioral questions (teamwork, leadership, problem-solving, failure).
- Use the STAR method (Situation, Task, Action, Result) to structure your answers.
- Research Twitch's company culture and values.
- Be ready to discuss your career goals and why you're interested in this role.

## Round 4: Advanced Technical Deep Dive
**Type:** Advanced Technical Interview · **Difficulty:** Hard · **Duration:** 60 min
Deep dive into advanced technical topics.
This is an advanced technical round, often focusing on a specific area relevant to the role or a more complex system design problem. It might involve deep dives into performance optimization, concurrency, specific technologies, or architectural decisions. The interviewer will challenge your assumptions and probe for deep understanding.
**Interviewers look for:** Deep expertise in relevant technologies (e.g., distributed systems, specific programming languages, cloud infrastructure).; Ability to tackle complex and ambiguous problems.; Leadership qualities and ability to drive technical initiatives.; Mentorship capabilities.; Strategic thinking.
**Evaluation criteria:** Depth of technical knowledge.; Ability to handle ambiguity.; Problem-solving in specialized domains.; Leadership and ownership.; Communication of complex technical ideas.
**Common rejection reasons:** Lack of deep technical expertise in specific areas.; Inability to handle complex, ambiguous problems.; Poor communication of technical concepts.; Not demonstrating leadership or ownership.
## Questions

- Design a distributed rate limiter for a large-scale API.
- How would you debug a performance issue in a microservices architecture?
- Discuss the challenges of maintaining consistency in a highly available distributed system.

## Preparation tips

- Revisit advanced topics in your area of expertise.
- Prepare to discuss complex architectural decisions and their trade-offs.
- Think about how you would lead and mentor other engineers on complex projects.
- Be ready for highly challenging, open-ended problems.