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In office • San Francisco💼 Full-time🗓 2026-06-25

Core

Building novel AI-driven product experiences and scalable backend systems for a conversation-first language learning app.

Role type

Senior Backend Engineer (full-stack capable)

Builds

Scalable backend systems and AI-driven product experiences for a consumer language learning app

Domain

EdTech / AI / Language Learning

Deliverable

production ML models | product features

Required skills

Backend engineering, full-stack engineering, scalable system design, debugging complex streaming issues, rapid development, feature ownership, mentoring engineers, product sense

Preferred skills

Experience building apps with 1M+ users

Technologies

None explicitly stated

Responsibilities

Building novel AI-driven product experiences and user interfaces, creating scalable backend systems, debugging complex streaming issues, owning the entire development cycle of features, coaching and mentoring other engineers

Seniority

Senior, hands-on IC

Rewrite
## About us Our mission is to reinvent the way people learn, starting with language. Learning a language can change a life by opening doors to new cultures, careers, and communities. Two billion people around the world are actively trying to learn a language, but the best way to learn (one-on-one tutoring) is hard to access at scale and hasn't been meaningfully improved in decades. Speak is building a human-level, AI-powered tutor in your pocket: a conversation-first experience that lets learners actually speak, get instant feedback, and progress through carefully designed lessons. The result is a complete path from beginner to confident speaker across multiple languages. Speak first launched in South Korea in 2019, where Speak has now become the number one language learning app, and we now serve learners across many markets and 15+ languages. Speak is one of the world's leading AI companies, with over $150m raised in venture investment from OpenAI, Accel, Founders Fund, Khosla Ventures, and more, with a distributed team across San Francisco, Seoul, Tokyo, Taipei, and Ljubljana. ## About this role We are looking for a senior backend focused but full-stack capable engineer to work on building novel AI-powered product experiences. The ideal candidate will have experience working in close coordination with product, design, and machine learning teams, as well as have a background in building polished consumer applications. This role sits at the center of developing our newest products focused on programmatic, conversationally-driven language learning and will be an instrumental contributor to the future of our company. ## What you'll be doing - Building novel AI-driven product experiences and user interfaces on the web - Full-stack engineering, but focused on creating scalable backend systems - Debugging complex streaming issues - Owning the entire development cycle of features, from conception to production - You'll be able to write code very quickly, ship frequently, and make a huge impact on our business by helping us scale our content ## What we're looking for - 5+ years of industry experience working as a Backend Engineer, preferably in a fast-paced startup environment - bonus: worked on an app that has been used by 1M users - Excellent problem-solving and communication skills, and the ability to work independently or as part of a team - Coach and mentor other engineers - Strong product sense: ability to think broadly/cross-functionally about product experiences ## Why work at Speak - Join a fantastic, tight-knit team at the right time: we're growing very quickly, we've most recently raised our Series C from some of the top investors in the valley, and we've achieved product-market fit in our initial markets. You'd join at a magical time when a single person could significantly change the course of the company. - Do your life's work with people you'll love working with: we care strongly about our craft and want every person at Speak to feel like they're growing every day
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