Scale Engineer

Software Engineer

Software EngineerSoftware Engineer IIMedium to Hard

This interview process is designed to assess candidates for a Software Engineer II position at Duolingo. It evaluates technical skills, problem-solving abilities, cultural fit, and experience relevant to building and scaling educational technology products.

Rounds·3

Timeline·~10d

Experience·2 - 5 yrs

Comp band·US$110000 - US$140000

Interview time·150 min

Evaluation

What they measure.

  • Problem-solving approach and clarity of thought.
  • Code quality, efficiency, and correctness.
  • Understanding of algorithms and data structures.
  • Ability to design scalable and maintainable systems.
  • Communication skills and ability to articulate technical concepts.
  • Cultural fit and alignment with Duolingo's values.
  • Experience and relevance to the role's requirements.

Preparation

How to prepare.

Tips

  1. Review fundamental data structures and algorithms (arrays, linked lists, trees, graphs, hash maps, sorting, searching).
  2. Practice coding problems on platforms like LeetCode, HackerRank, or Coderbyte, focusing on medium-difficulty problems.
  3. Understand common software design patterns and principles (SOLID, DRY, KISS).
  4. Brush up on system design concepts, including scalability, reliability, and distributed systems.
  5. Prepare to discuss your past projects, highlighting your contributions, challenges, and learnings.
  6. Research Duolingo's technology stack and product offerings.
  7. Practice behavioral questions using the STAR method (Situation, Task, Action, Result).

Study plan

Fig · Study plan — 03 phases

01 / 03
01

Phase 01 of 03

Data Structures and Algorithms Fundamentals

Weeks 1-2: Data Structures & Basic Algorithms. Practice implementations and problem-solving.

Weeks 1-2: Focus on core data structures (arrays, linked lists, stacks, queues, trees, graphs, hash tables) and their common operations and time complexities. Practice implementing them and solving problems related to them. Review basic algorithms like sorting (quicksort, mergesort) and searching (binary search).

Questions

Commonly asked.

  • Tell me about a challenging project you worked on and how you overcame obstacles.
  • How would you design a system to track user progress in Duolingo?
  • What are your favorite programming languages and why?
  • Describe a time you had to debug a complex issue.
  • How do you approach learning new technologies?
  • What interests you about working at Duolingo?
  • If you could improve one aspect of the Duolingo app, what would it be and why?
  • Explain the concept of recursion with an example.
  • How would you optimize a database query?
  • Describe your experience with cloud platforms like AWS or GCP.

Locations

Regional differences.

Fig · Regions — 02 locations

01 / 02

Location

Global

Interview focus

Understanding of core computer science principles and data structures.Ability to design scalable and maintainable software solutions.Experience with web development frameworks and cloud technologies.Problem-solving and debugging skills.Communication and collaboration skills.

Common questions

  • How would you approach building a feature for Duolingo that personalizes learning paths based on user performance?
  • Describe a time you had to optimize a slow-performing piece of code. What was the issue and how did you resolve it?
  • How do you ensure the quality and reliability of your code in a large-scale application?
  • What are your thoughts on A/B testing new features for a product like Duolingo?
  • Tell me about a challenging technical problem you solved that involved distributed systems.

Tips

  • Familiarize yourself with Duolingo's product and mission.
  • Be prepared to discuss your past projects in detail, focusing on your contributions and the impact.
  • Practice coding problems, especially those involving algorithms and data structures.
  • Research common cloud platforms (AWS, GCP, Azure) if relevant to the role.
  • Prepare questions to ask the interviewer about the team, technology stack, and company culture.

Rounds

Round-by-round.

Expand a step for evaluation criteria, sample questions, and prep notes.

DSA

Coding questions at Duolingo.

Frequently reported on Duolingo loops

View all at Duolingo

Other guides

More at Duolingo.