Duolingo interview, code you didn't write.
Updated · Sources at the end
Duolingo publishes its engineering interview round by round, and two rounds set it apart. In pair programming, 75 minutes long, you work on a coding problem inside a codebase similar to what Duolingo uses in production, alongside an engineer: the point, in Duolingo's words, is to work with code written by other engineers and learn on your feet. In code review, 60 minutes on CodeSignal, you find the issues in a set of code changes and suggest improvements. Both come in backend, iOS and Android versions.
Around them sit a 60-minute algorithm interview in CodeSignal and a 60-minute design round with no coding, and new graduates add an online coding task and a whiteboard round. Duolingo's post says interviewers are not there to trick you and will give hints if you get stuck. Since its 2025 AI-first memo, Duolingo says headcount is given only when a team cannot automate more of its work, and AI use is part of what it looks for in hiring.
Free · 2 minutes · no account
The questions for your exact Duolingo role and level.
Interviewing at Duolingo? Below are the questions built from what it says it tests. For the ones your exact role and level will get, paste the posting. Your first mock is free.
Who Duolingo hires
Duolingo had more than 900 employees at the end of 2025, more than 430 of them engineers, and revenue of $1.04 billion that year; daily active users grew 23% in the second quarter of 2026. On 4 October 2026 it had 59 open roles, 19 in engineering: backend, Android, iOS, platform and site reliability engineers, an AI research engineer, engineering managers and technical programme managers. Nearly all are in New York and Pittsburgh, with a group in Beijing; Berlin and Seattle had almost no engineering openings. Product managers, designers and data scientists are hired too.
What is the Duolingo interview process?
Duolingo's engineering blog lays out the rounds, with durations and platforms, in an August 2024 post. It says each role has its own interview plan, split into pre-onsite sessions and a virtual onsite that can run over two or more days. New-grad and intern details come from 2025 and 2026 candidates.
Duolingo says its recruiters review every resume themselves and stay your main point of contact.
Graded on correct output and time efficiency. Candidates report it on CodeSignal; one new grad scored 600 out of 600 and was still rejected.
New grads and internsCandidates in 2025 and 2026 report it before the onsite, and one was asked to give a detailed approach before coding. A redo was offered and both attempts were considered.
New grads and interns, reportedAn algorithm problem with a Duolingo engineer.
A coding problem inside a codebase similar to production. Read the existing code before changing it, and talk through what you find with your pair.
Find the issues in a set of code changes and suggest improvements, in a backend, iOS or Android version.
Problem solving out loud. One 2025 new grad sat code review, whiteboard and pair programming back to back, about five hours in all.
New grads and internsBackend system design, or iOS and Android app architecture.
Experienced hiresWhat Duolingo screens for
Duolingo's posts and job ads point to what it looks for.
- Working in code other engineers wrote, and learning on your feet
- A careful eye for code quality in review
- Clear thinking out loud, with or without hints
- Using AI in your work: part of what Duolingo looks for since 2025
- Taking a hint well: Duolingo says interviewers will help if you get stuck
Duolingo interview questions
Drawn from what they say they testDuolingo publishes the rounds rather than the questions. These practice questions follow the round formats it describes, and the behavioural ones follow what those rounds test.
Behavioural & motivation
- Why Duolingo?Listening for: Specificity · Connection · Research
- Tell me about a time you had to change code you didn't write and didn't fully understand.Listening for: How you explored it · A safe change · Leaving it better
- Tell me about a code review where you disagreed with the author.Listening for: The real issue · How you said it · How it ended
- How do you use AI tools in your work today?Listening for: Concrete use · How you check it · Where it falls short
Technical
- Practice: you are given a small service that awards streak bonuses to learners. A bug report says some users lose their streak at midnight in their own time zone. Find the cause and fix it, talking through the code as you read it.Pair programming in an existing codebase: Duolingo's 75-minute round: a coding problem in a codebase similar to productionListening for: Reads before writing · A correct fix · Proves it
- Practice: review a change that adds a cache in front of a lesson-loading endpoint. What do you check, and what would you ask the author to change?Code review: Duolingo's 60-minute round on CodeSignal: find issues and suggest improvements to a set of changesListening for: Correctness · Design and readability · Prioritised feedback
- Practice: design the service that decides which lesson a learner sees next, for tens of millions of daily users.System design: Duolingo's 60-minute design round, backend or mobile architecture, no codingListening for: The data · Scale · Changing it safely
These come from what the company says it tests, and your loop is role-specific. Paste the actual posting and Calibrd predicts the questions for that exact role and level.
Predict my Duolingo questions →Pay
Base salary ranges posted in Duolingo's job ads on 4 October 2026, for New York and Pittsburgh. Duolingo says base salary is supplemented by equity.
How to prepare for a Duolingo interview
- Practise reading an unfamiliar codebase quickly: run it, find the entry point, then change one thing safely.
- Do two or three timed code reviews of real pull requests, writing short, prioritised comments.
- Practise on CodeSignal; Duolingo's technical screen and code review run there.
- For new-grad roles, prepare for a Karat first round and a five-hour onsite of code review, whiteboard and pair programming.
- Prepare an honest answer on how you use AI tools in your work.
- Use only official emails: Duolingo warns that real recruiters write from @duolingo.com or @recruiting.duolingo.com.
This guide covers Duolingo's software engineering interviews in New York and Pittsburgh, for experienced hires, new graduates and interns. Product designers follow a separate portfolio-based process. For management and leadership roles the loop is similar but the bar shifts to people, delivery and strategy, so pair it with the leadership interview prep hub. The bar for your exact role comes from the role-by-role guides, and the prep that actually transfers is spoken, so run a mock interview before the real one.
Also interviewing at P&G? Its guide follows the same format, from the first screen to the offer.
Knowing the questions isn’t the same as answering them out loud. Run a Duolingo mock: spoken answers, coached on the spot. Your first mock is free.
Run a Duolingo mock →FAQ & sources
What is Duolingo's interview process?
Duolingo's engineering blog lays out the rounds, with durations and platforms, in an August 2024 post. The stages, in order: Resume review and recruiter; Online coding task; Karat interview; Technical video interview; Pair programming; Code review; Whiteboard; Design.
What does Duolingo look for in candidates?
Duolingo's posts and job ads point to what it looks for. Working in code other engineers wrote, and learning on your feet; A careful eye for code quality in review; Clear thinking out loud, with or without hints; Using AI in your work.
What questions does Duolingo ask in interviews?
Duolingo publishes the rounds rather than the questions. Technical themes: Pair programming in an existing codebase; Code review; System design.
How do I prepare for a Duolingo interview?
Practise reading an unfamiliar codebase quickly: run it, find the entry point, then change one thing safely. Do two or three timed code reviews of real pull requests, writing short, prioritised comments.
- 01Duolingo, Interviewing with Duolingo's engineering team (August 2024)every round with its duration and platform, pair programming in a production-like codebase, code review, design, the new-grad rounds and hints from interviewers.
- 02Duolingo, Product design interviews (May 2023)the separate design process.
- 03Duolingo open roles59 roles on 4 October 2026, 19 in engineering, the posted salary ranges, equity and the fraud warning.
- 04Duolingo, 2025 annual report (10-K)more than 900 employees, more than 430 engineers.
- 05Duolingo, Q2 2026 shareholder letterdaily active users up 23%.
- 06The Verge, Duolingo goes AI-first (April 2025)headcount only when a team cannot automate more, and AI use in hiring.
- 07Reddit, Duolingo Karat interview (October 2025)a detailed approach before coding, and the redo.
- 08Reddit, Duolingo new-grad onsite (October 2025)code review, whiteboard and pair programming back to back.
- 09Reddit, rejected after a perfect assessment (November 2025)600 out of 600 on the CodeSignal assessment, then a rejection.
- 10Reddit, Duolingo intern rejections (October 2026)rejections without an interview.
Interview processes change. This reflects widely-reported and sourced conditions as of 2026 — confirm specifics with your recruiter, and treat it as a map rather than a guarantee.
Prep for a real Duolingo role
Practise your Duolingo interview, out loud.
Paste a real Duolingo posting and Calibrd predicts the questions for that role and level, benchmarks the pay, and flags the gaps an interviewer will probe in your CV — then listens to your spoken answers and coaches them. Your first mock is free.
Free to start · No card · Encrypted at rest, never used to train AI, remove anytime