Backend Engineer, Payments

About the role

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're looking for a Staff Software Engineer to become Speak's first dedicated owner of subscription payments.

Millions of learners rely on Speak to improve their language skills, and our subscription systems power how they purchase, renew, and maintain access to the product. Getting payments right is critical to both the learner experience and our business.

Today, our payment infrastructure spans multiple providers and platforms, including Apple App Store, Google Play, RevenueCat, Paddle, and Stripe. As Speak expands internationally and introduces new subscription offerings, ensuring correctness and reliability across these systems becomes increasingly important.

You'll take ownership of this critical engineering domain, establishing the architecture, safeguards, monitoring, and engineering practices needed to make payments dependable at scale.

This isn't simply about integrating payment providers or building checkout flows. It's about ensuring that learners are charged the correct amount, cancellations are respected, entitlements stay consistent, and failures are detected and recovered from safely.

You'll work closely with Growth, Product, Finance, Support, and Platform Engineering. You'll have significant autonomy to identify the highest-impact problems, shape the technical roadmap, and build the foundation that allows other teams to ship monetization features confidently.

WHAT YOU'LL BE DOING

- Own subscription payments end-to-end. Take technical ownership of the purchase, renewal, cancellation, refund, and entitlement lifecycles across mobile and web.

- Build reliable payment infrastructure. Design and improve backend systems integrating with RevenueCat, Paddle, Stripe, Apple, and Google Play, ensuring consistency across providers and internal systems.

- Make payment correctness a first-class engineering priority. Implement safeguards such as idempotent processing, reliable webhook handling, safe retries, transaction reconciliation, and automated recovery to prevent incorrect charges and lost entitlements.