Top 25
Prep plan
Updated weekly · Last refresh Aug 30

Duolingo Mobile Engineer Interview Questions

The questions to prepare for a Duolingo Mobile Engineer interview. Questions from real interview reports rank first. Updated weekly.

25questions
~4htotal time
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1
CodingStart here. 9 questions · ~79 min
Two Sum with TargetEasy
Practice

Use a hash map to find two array elements that sum to a target in O(n) time.

Hash TablesArraysStringsDuolingo
Design Self-Defined Game UIMedium

Tests UI design thinking, implementation skills, and ability to translate content into a usable interface.

ArraysStringsMatrixDuolingo
Fetch File, Render, Run GameMedium

Tests networking, parsing/rendering, and end-to-end integration of a simple game flow.

Hash TablesArraysStringsDuolingo
Implement a Word Search GameHard

Tests ability to build game logic and handle core data structures and UI interactions.

RecursionStringsMatrixDuolingo
Handle API Errors in MobileMedium

Tests resilience patterns, user experience for failures, and robust error handling in mobile networking.

Hash TablesArraysStringsDuolingo
Synchronous vs Asynchronous ProgrammingMedium

Tests understanding of concurrency models and their implications for responsiveness and correctness in mobile apps.

QueueArraysStringsDuolingo
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2
Behavioral & Leadership15 questions · ~131 min
Raising Code Quality StandardsEasy

Tests ownership of code quality, balancing engineering standards with delivery speed, and communicating changes that improve reliability.

Stakeholder ManagementCommunicationOwnershipDuolingo
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3
More topics1 question · ~9 min
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