Senior/iOS Engineer II

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.

About the role

We are hiring for multiple levels for any one of the following teams. Leveling is usually determined once all interviews are completed.

Notifications Team:
As an iOS engineer on the Notifications team, you will build features that empower learners to build long-term habits by improving how we schedule, personalize, and deliver notifications. You will design and implement meaningful notification experiences while collaborating with backend, data science, and product teams. Notifications are fundamental to Duolingo, and we’re looking for engineers who are energized about experimenting and shipping features end‑to‑end.

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.

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
• Knowledge of iOS SDK performance tools and optimization techniques

Salary details: The posted range is $177,700 – $240,400 USD. The base salary is supplemented by equity compensation.