# Software Engineer
**Role:** Software Engineer · **Level:** L3
**Company:** [Patreon](https://scaleengineer.com/companies/patreon)
**Difficulty:** Medium
**Salary:** US$100000 - US$130000
**Experience:** 1 - 3
**Timeline:** ~7 days
The interview process for a Software Engineer (L3) at Patreon is designed to assess a candidate's technical skills, problem-solving abilities, cultural fit, and potential for growth within the company. It typically involves multiple rounds, starting with an initial HR screen, followed by technical interviews, and concluding with a hiring manager or team lead discussion.
Canonical: https://scaleengineer.com/interviews/patreon/l3-software-engineer
---
## Overall evaluation

- Technical Proficiency
- Communication & Collaboration
- Cultural Fit & Motivation

## Questions asked

- Write a function to reverse a linked list.
- Given an array of integers, find the two numbers that add up to a specific target.
- Explain the difference between a process and a thread.
- Describe a situation where you had to deal with ambiguity in a project.
- How would you design a URL shortener service?
- What are the advantages of using a NoSQL database over a SQL database in certain scenarios?
- Tell me about a time you failed. What did you learn from it?
- How do you stay updated with new technologies and programming trends?

## 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 Coderbyte, focusing on medium-difficulty problems.
- Understand core computer science concepts such as time and space complexity (Big O notation).
- Familiarize yourself with object-oriented programming (OOP) principles.
- Prepare to discuss your past projects and experiences in detail, highlighting your contributions and learnings.
- Research Patreon's products, mission, and values to understand how your skills align.
- Prepare questions to ask the interviewer about the role, team, and company culture.

### studyPlan

- {"title":"Data Structures","longDescription":"Weeks 1-2: Focus on Data Structures. Cover arrays, linked lists, stacks, queues, hash tables, trees (binary trees, BSTs, AVL trees), and graphs. Understand their operations, time/space complexity, and common use cases. Practice implementing these structures and solving problems related to them.","shortDescription":"Weeks 1-2: Data Structures (Arrays, Lists, Trees, Graphs, Hash Tables). Focus on complexity and implementation."}
- {"title":"Algorithms","longDescription":"Weeks 3-4: Focus on Algorithms. Cover sorting algorithms (bubble sort, merge sort, quicksort), searching algorithms (binary search, linear search), graph traversal (BFS, DFS), dynamic programming, and greedy algorithms. Practice solving problems that require applying these algorithms.","shortDescription":"Weeks 3-4: Algorithms (Sorting, Searching, Graph Traversal, DP, Greedy). Practice problem-solving."}
- {"title":"System Design Fundamentals","longDescription":"Week 5: System Design Fundamentals. Understand concepts like scalability, availability, reliability, load balancing, caching, databases (SQL vs. NoSQL), and API design. For an L3 role, focus on understanding basic system components and trade-offs rather than deep architectural design.","shortDescription":"Week 5: System Design Basics (Scalability, Caching, Databases, APIs). Understand components and trade-offs."}
- {"title":"Behavioral Preparation","longDescription":"Week 6: Behavioral and Situational Questions. Prepare to discuss your past experiences using the STAR method (Situation, Task, Action, Result). Reflect on examples of teamwork, problem-solving, handling conflict, and learning from mistakes. Align your answers with Patreon's values.","shortDescription":"Week 6: Behavioral Questions (STAR Method). Prepare examples for teamwork, problem-solving, and conflict."}
- {"title":"Final Preparation","longDescription":"Week 7: Mock Interviews and Company Research. Conduct mock interviews to simulate the actual interview environment. Refine your answers and practice articulating your thought process. Deep dive into Patreon's website, blog, and recent news to understand their business and culture.","shortDescription":"Week 7: Mock Interviews & Company Research. Practice articulation and understand Patreon's business."}

## Location differences

- {"location":"Remote","differences":{"tips":["Ensure a stable internet connection and a quiet environment for remote interviews.","Be prepared to articulate your thought process clearly, as non-verbal cues might be less apparent.","Highlight experience with remote work tools and methodologies."],"interviewFocus":["Adaptability to remote collaboration tools and practices.","Understanding of distributed systems and asynchronous communication.","Proactive communication and self-management skills."],"commonQuestions":["How would you handle a situation where a feature you developed is causing performance issues in production?","Describe a time you had to work with a difficult stakeholder. How did you manage the relationship?","What are your thoughts on test-driven development (TDD)?"]}}
- {"location":"On-site (e.g., San Francisco)","differences":{"tips":["Be ready to whiteboard solutions to coding problems.","Engage actively with interviewers and ask clarifying questions.","Showcase your passion for technology and continuous learning."],"interviewFocus":["Deep understanding of core computer science principles.","Ability to design and implement efficient algorithms.","Problem-solving skills in a collaborative, in-person environment."],"commonQuestions":["Tell me about a challenging technical problem you solved recently.","How do you approach debugging a complex issue?","What are your favorite programming languages and why?"]}}

## Round 1: HR Introduction
**Type:** HR Screen · **Difficulty:** Easy · **Duration:** 30 min
An introductory call with HR to discuss your background, interest in Patreon, and basic qualifications.
This initial screening call with an HR representative is designed to understand your background, career aspirations, and motivation for applying to Patreon. They will also provide an overview of the role and the interview process. It's an opportunity to ask initial questions about the company culture, benefits, and the role itself.
**Interviewers look for:** Clear and concise communication.; Genuine interest in Patreon.; Basic understanding of the software engineering field.; Professionalism and positive attitude.
**Evaluation criteria:** Basic communication skills.; Understanding of the role and company.; Enthusiasm for the opportunity.; Alignment with basic company values.
**Common rejection reasons:** Poor communication skills.; Inability to articulate thought process.; Lack of basic understanding of core CS concepts.; Unprofessional demeanor.
## Questions

- Tell me about yourself and your career goals.
- Why are you interested in Patreon?
- What are your salary expectations?
- What are your strengths and weaknesses?

## Preparation tips

- Be prepared to talk about your resume and career goals.
- Research Patreon's mission, values, and products.
- Prepare a few questions to ask the recruiter.
- Ensure you are in a quiet environment with good reception/internet connection.

## Round 2: Coding Challenge
**Type:** Technical Interview (Coding) · **Difficulty:** Medium · **Duration:** 60 min
Solve coding problems focusing on data structures, algorithms, and clean code implementation.
This round focuses on your core technical skills. You will typically be asked to solve one or two coding problems, often involving data structures and algorithms. The interviewer will assess your ability to understand the problem, devise a solution, implement it in code, and explain your reasoning and the complexity of your solution. Expect to use a collaborative coding environment or a whiteboard.
**Interviewers look for:** Logical thinking and systematic problem-solving.; Correct and efficient implementation of algorithms.; Clear explanation of the solution and trade-offs.; Ability to write testable code.; Attention to detail.
**Evaluation criteria:** Problem-solving approach.; Coding proficiency (syntax, logic, efficiency).; Understanding of data structures and algorithms.; Ability to write clean, readable, and maintainable code.; Handling of edge cases and constraints.
**Common rejection reasons:** Inability to solve coding problems efficiently.; Poor understanding of data structures and algorithms.; Code does not compile or has significant bugs.; Difficulty explaining the thought process behind the solution.; Not considering edge cases or constraints.
## Questions

- Given a binary tree, find its inorder traversal.
- Implement a function to find the kth smallest element in an unsorted array.
- Write a function to check if a string is a palindrome.

## Preparation tips

- Practice coding problems on platforms like LeetCode, focusing on medium difficulty.
- Review common data structures (arrays, linked lists, trees, graphs, hash maps) and algorithms (sorting, searching, graph traversal).
- Understand Big O notation for time and space complexity.
- Practice explaining your thought process out loud as you code.
- Be prepared to discuss trade-offs of different approaches.

## Round 3: System Design
**Type:** Technical Interview (System Design) · **Difficulty:** Medium · **Duration:** 60 min
Design a scalable system, focusing on components, trade-offs, and basic architectural principles.
This round assesses your ability to think about larger systems. You'll be given a high-level problem (e.g., design a URL shortener, a social media feed, or a rate limiter) and asked to design a solution. The focus is on understanding requirements, identifying components, discussing trade-offs, and considering scalability and reliability. For an L3 role, the expectation is more about understanding fundamental concepts and making reasonable design choices rather than architecting massive distributed systems.
**Interviewers look for:** Structured approach to system design.; Knowledge of common design patterns and architectural choices.; Ability to justify design decisions.; Understanding of scalability and performance considerations.; Pragmatism in solution design.
**Evaluation criteria:** Ability to design scalable and reliable systems.; Understanding of system components (databases, APIs, caching, load balancers).; Consideration of trade-offs and constraints.; Clear communication of design decisions.; Problem decomposition skills.
**Common rejection reasons:** Lack of understanding of system design principles.; Inability to break down a complex problem into smaller components.; Poor consideration of scalability, reliability, and trade-offs.; Difficulty communicating design choices.; Overly simplistic or overly complex solutions.
## Questions

- Design a system to count unique visitors to a website.
- How would you design a basic API for a task management application?
- Explain the concept of caching and where you might use it.

## Preparation tips

- Study system design concepts: scalability, availability, databases (SQL vs. NoSQL), caching, load balancing, APIs.
- Practice designing common systems like Twitter feed, TinyURL, or a chat application.
- Focus on understanding the trade-offs of different design choices.
- Be prepared to draw diagrams and explain your design clearly.

## Round 4: Hiring Manager Discussion
**Type:** Behavioral & Manager Interview · **Difficulty:** Medium · **Duration:** 45 min
Discuss behavioral examples, team fit, and career aspirations with the hiring manager.
This final round is typically with the hiring manager or a senior member of the team. It's a chance to discuss your experience in more depth, understand team dynamics, and assess cultural fit. You'll be asked behavioral questions to understand how you approach work, collaborate with others, and handle challenges. It's also your opportunity to ask in-depth questions about the team's projects, challenges, and culture.
**Interviewers look for:** Positive attitude and collaborative spirit.; Examples of successful teamwork and problem-solving.; Self-awareness and a growth mindset.; Alignment with company mission and values.; Clear career aspirations.
**Evaluation criteria:** Alignment with Patreon's values and culture.; Behavioral competencies (teamwork, communication, problem-solving).; Motivation and passion for the role and company.; Career growth potential.; Ability to handle challenges and feedback.
**Common rejection reasons:** Poor cultural fit.; Lack of enthusiasm or motivation.; Inability to articulate past experiences effectively.; Negative attitude towards previous employers or colleagues.; Mismatch in career goals or expectations.
## Questions

- Tell me about a time you had a conflict with a teammate and how you resolved it.
- Describe a project you are particularly proud of and your role in it.
- How do you handle constructive criticism?
- What are your long-term career aspirations?

## Preparation tips

- Prepare specific examples using the STAR method for behavioral questions.
- Reflect on your career goals and how this role aligns with them.
- Think about what you're looking for in a team and manager.
- Prepare thoughtful questions about the team's work, challenges, and culture.