Our mission at Duolingo is to develop the best education in the world and make it universally available. It’s a big mission, and that’s where you come in!

At Duolingo, you’ll join a team that cares about finding innovative solutions to complex technical problems, running countless experiments (300+ at a time!) with our massive user base to make data-driven decisions, and educating our users and employees alike. You’ll have limitless learning opportunities, mentorship and collaboration with world-class minds, and a variety of projects with large scopes — while doing work that’s both fun and meaningful.

Join our life-changing mission to develop education for our half a billion (and growing!) learners around the world.

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About the role

Ads Team: Duolingo's Monetization pillar builds the systems that fund our mission: from subscription packaging and advertising to ML-powered personalization and beyond. As a Senior iOS Engineer on Ads, you'll work on a product engineering team responsible for growing and scaling Duolingo's ads business: bringing high-quality ads that delight learners, fit seamlessly into our product experience, and meaningfully contribute to Duolingo’s bottom line. The team will own the systems behind ad serving, mediation and demand, in-product ad formats and surfaces, and more. You'll work cross functionally with product, design, data science, machine learning, and ad operations.

IAP Team:

The In App Purchases team owns Duolingo’s in-app purchase business: the gem economy, the shop, and avatar cosmetics and collectibles. You’ll build purchase flows and the systems behind them, then prove out what works through experimentation. Avatar cosmetics and collectibles are our new initiatives to drive DAU aligned monetization.

Score Team:

Duolingo Score is how we reflect a learner's real language proficiency back to them. As an engineer on this small, high-impact team, you'll help make learners care about their score as much as they care about their streak. You'll partner closely with the Score Pillar's product and design team and our backend and Android engineers, working on the systems that power score calculation, proficiency modeling, and how score surfaces across the app — including integrations with external platforms like LinkedIn, so learners can showcase their proficiency beyond Duolingo.

🧠 You will...

• Collaborate on software projects with product design and backend aspects
• Develop, release, and maintain native iOS applications, primarily in Swift
• Mentor and set technical direction for junior engineers across the company

✅ You have...

• A Bachelor’s degree in Computer Science or a related technical field
• A solid foundation in computer science with strong competencies in data structures, algorithms, and software design
• Programming experience in Swift

⭐ Exceptional candidates will have...

• Strong proficiency in Swift, with proven ability to build and maintain production-level applications
• Strong technical knowledge of iOS mobile application development for iPhone/iPad using Swift with Cocoa Touch and related frameworks
• Experience designing clean and maintainable APIs
• Experience with multithreaded programming
• Experience writing unit tests and testable code
• Knowl