Senior Software Engineer, Backend (Score)

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.

Duolingo Score is how we reflect a learner's real language proficiency back to them. As the team lead / backend 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 iOS 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...

• Lead a small team (3 engineers including yourself), owning both technical direction and day-to-day execution
• Touch critical backend services like user-tree-backend and session-generator, which define score calculation, proficiency modeling, and multiple score entry points across the learning app
• Collaborate on software projects with product and design
• Develop, release, and maintain backend services and/or infrastructure
• Work closely with multiple pillars — including Growth, Learning, and Score — to build your impact and visibility
• Lead individual and team project priorities and milestones, ensuring we're always shipping

✅ You have...

• A Bachelor's degree in Computer Science or a related technical field
• Strong competencies in data structures, algorithms, and software design
• Experience programming in Java, Python, or Kotlin
• Solid understanding of one or more database technologies
• Interest in growing into (or continuing to develop as) a technical team lead

⭐ Exceptional candidates will have...

• Experience working with product and design teams to improve engagement
• Prior experience leading or mentoring engineers on a small team