Affirm

Software Engineer 1

Software EngineerL4Medium

The Software Engineer 1 (L4) interview at Affirm is designed to assess a candidate's foundational software engineering skills, problem-solving abilities, and cultural fit. It typically involves a mix of technical and behavioral assessments to ensure the candidate can contribute effectively to Affirm's engineering teams.

Rounds

3

Timeline

~10 days

Experience

2 - 5 yrs

Salary Range

US$110000 - US$140000

Total Duration

135 min

Overall Evaluation Criteria

Technical Skills

Problem-solving approach
Coding proficiency (clean, efficient, well-structured code)
Understanding of data structures and algorithms
System design principles (for relevant roles/levels)
Communication skills
Collaboration and teamwork
Cultural alignment with Affirm's values (e.g., empathy, ownership, growth)

Communication

Ability to articulate thought process
Clarity in explaining technical concepts
Active listening
Ability to ask clarifying questions

Collaboration & Teamwork

Demonstrated ability to work effectively in a team
Handling of disagreements and conflicts
Contribution to team success
Proactiveness and initiative

Cultural Fit

Alignment with Affirm's mission and values
Demonstration of ownership and accountability
Growth mindset and willingness to learn
Empathy towards users and colleagues

Preparation Tips

1Review fundamental data structures (arrays, linked lists, trees, graphs, hash maps) and algorithms (sorting, searching, dynamic programming, graph traversal).
2Practice coding problems on platforms like LeetCode, HackerRank, or Coderbyte, focusing on medium-difficulty problems.
3Brush up on core computer science concepts such as operating systems, databases, and networking.
4Prepare for behavioral questions using the STAR method (Situation, Task, Action, Result).
5Understand Affirm's business, products, and engineering culture.
6Prepare questions to ask the interviewer about the role, team, and company.

Study Plan

1

Data Structures & Complexity

Weeks 1-2: Data Structures (Arrays, Lists, Trees, Graphs, Hash Tables) & Complexity Analysis.

Weeks 1-2: Focus on Data Structures. Cover arrays, linked lists, stacks, queues, hash tables, trees (binary trees, BSTs, heaps), and graphs. Practice implementing these and solving problems related to them. Understand time and space complexity (Big O notation).

2

Algorithms & Problem Solving

Weeks 3-4: Algorithms (Sorting, Searching, DP, Graphs) & Problem Solving.

Weeks 3-4: Focus on Algorithms. Cover sorting algorithms (quicksort, mergesort), searching algorithms (binary search), recursion, dynamic programming, greedy algorithms, and graph algorithms (BFS, DFS, Dijkstra's). Practice solving problems using these algorithms.

3

System Design Fundamentals

Week 5: System Design Basics (Scalability, Databases, Caching, APIs).

Week 5: System Design Fundamentals. Understand concepts like scalability, availability, reliability, load balancing, caching, databases (SQL vs. NoSQL), and APIs. Practice designing common systems like a URL shortener or a Twitter feed.

4

Behavioral & Mock Interviews

Week 6: Behavioral Questions (STAR method) & Mock Interviews.

Week 6: Behavioral Preparation & Mock Interviews. Prepare answers for common behavioral questions using the STAR method. Focus on demonstrating ownership, teamwork, and problem-solving. Conduct mock interviews to simulate the actual interview experience.

Commonly Asked Questions

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 store and retrieve user profiles.
Explain the concept of RESTful APIs.
Tell me about a time you failed and what you learned from it.
How would you optimize a slow database query?
Describe your experience with version control systems like Git.

Location-Based Differences

San Francisco, USA

Interview Focus

Emphasis on practical coding skills and understanding of core CS concepts.Assessment of collaboration and communication skills in a team setting.

Common Questions

How would you design a URL shortener?

Explain the difference between a process and a thread.

Describe a challenging technical problem you solved and how you approached it.

Tell me about a time you disagreed with a teammate and how you resolved it.

Tips

Be prepared to whiteboard solutions for common data structures and algorithms problems.
Practice explaining your thought process clearly and concisely.
Research Affirm's products and values to tailor your behavioral answers.

Remote (Global)

Interview Focus

Greater emphasis on system design and scalability for more experienced candidates.Assessment of adaptability and problem-solving in complex scenarios.

Common Questions

How would you design a system to handle real-time notifications?

Discuss the trade-offs between SQL and NoSQL databases.

Describe a project where you had to optimize performance. What techniques did you use?

How do you handle ambiguity in project requirements?

Tips

Prepare for system design questions, focusing on trade-offs and scalability.
Be ready to discuss your experience with distributed systems and cloud technologies.
Highlight instances where you've taken initiative and driven projects forward.

Process Timeline

1
Data Structures & Algorithms45m
2
System Design & Architecture45m
3
Behavioral Interview45m

Interview Rounds

3-step process with detailed breakdown for each round

1

Data Structures & Algorithms

Coding challenge focused on data structures and algorithms.

Technical (Coding)Medium
45 minSoftware Engineer

This round typically involves a coding challenge, often presented as a problem to solve on a shared editor or whiteboard. The interviewer will assess your ability to translate a problem into code, your understanding of data structures and algorithms, and your approach to testing and debugging. Expect to discuss your solution and its time/space complexity.

What Interviewers Look For

A structured approach to problem-solvingClean, efficient, and correct codeAbility to explain the solution and its trade-offsBasic understanding of CS fundamentals

Evaluation Criteria

Problem-solving approach
Coding proficiency
Understanding of data structures and algorithms
Communication clarity

Questions Asked

Given a string, find the length of the longest substring without repeating characters.

StringSliding WindowHash Map

Implement a function to check if a binary tree is a Binary Search Tree (BST).

TreeRecursionBinary Search Tree

Preparation Tips

1Practice coding problems under timed conditions.
2Focus on writing clean, readable, and well-commented code.
3Be prepared to explain your code line by line.
4Think about edge cases and how to handle them.

Common Reasons for Rejection

Inability to articulate thought process
Poor coding practices (unreadable, inefficient code)
Fundamental misunderstanding of data structures or algorithms
Lack of enthusiasm or engagement
2

System Design & Architecture

System design problem to assess architectural thinking.

Technical (System Design)Medium
45 minSenior Software Engineer / Engineering Manager

This round assesses your ability to design scalable, reliable, and maintainable software systems. You'll be given an open-ended problem (e.g., design a social media feed, a URL shortener, or a rate limiter) and expected to discuss various components, data models, APIs, and trade-offs. The focus is on your thought process and ability to handle complexity.

What Interviewers Look For

A systematic approach to designing complex systemsUnderstanding of distributed systems conceptsAbility to identify and mitigate potential bottlenecksClear communication of design decisions and justifications

Evaluation Criteria

System design principles
Scalability and performance considerations
Trade-off analysis
Clarity of design explanation
Handling of constraints and requirements

Questions Asked

Design a system like TinyURL.

System DesignScalabilityDatabasesAPIs

Design a news feed system for a social media platform.

System DesignScalabilityCachingDatabases

Preparation Tips

1Study common system design patterns and architectures.
2Practice designing various types of systems.
3Focus on understanding trade-offs between different design choices.
4Be prepared to discuss databases, caching, load balancing, and message queues.

Common Reasons for Rejection

Inability to design scalable and reliable systems
Lack of consideration for trade-offs
Poor communication of design choices
Not addressing potential failure points
3

Behavioral Interview

Behavioral questions to assess fit and past experiences.

Behavioral & Cultural FitMedium
45 minHiring Manager / Senior Team Member

This round focuses on your past experiences and how they align with the role and Affirm's culture. You'll be asked behavioral questions designed to understand your work style, how you handle challenges, collaborate with others, and demonstrate key competencies. Use the STAR method to provide structured and specific answers.

What Interviewers Look For

Evidence of past behavior that predicts future performanceAlignment with Affirm's core valuesAbility to collaborate effectivelySelf-awareness and a growth mindset

Evaluation Criteria

Behavioral competencies (teamwork, problem-solving, initiative)
Cultural fit with Affirm's values
Communication and interpersonal skills
Motivation and career aspirations

Questions Asked

Tell me about a time you had to work with a difficult colleague. How did you handle it?

BehavioralTeamworkConflict Resolution

Describe a project where you took initiative beyond your defined responsibilities.

BehavioralOwnershipInitiative

What are your career goals for the next 3-5 years?

BehavioralCareer Goals

Preparation Tips

1Prepare stories for common behavioral questions (teamwork, conflict resolution, failure, success, leadership).
2Be honest and authentic in your responses.
3Connect your experiences to Affirm's values.
4Show enthusiasm for the role and the company.

Common Reasons for Rejection

Lack of alignment with company values
Poor communication or interpersonal skills
Inability to provide specific examples for behavioral questions
Negative attitude or lack of enthusiasm

Commonly Asked DSA Questions

Frequently asked coding questions at Affirm

View all
Group AnagramsMEDIUMValid AnagramEASYCoin ChangeMEDIUMInsert Delete GetRandom O(1)MEDIUMInsert Delete GetRandom O(1) - Duplicates allowedHARDString CompressionMEDIUMParse Lisp ExpressionHARDNumber of Recent CallsEASYShortest Uncommon Substring in an ArrayMEDIUMString Compression IIIMEDIUM