Backend Engineer, Payments

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.

• Proactively detect and resolve payment issues. Establish monitoring, alerting, and operational processes that catch billing inconsistencies and failures before they become widespread customer problems.

• Lead technical investigations and incident response. Diagnose complex production issues across payment providers, backend systems, and subscription state. Drive root-cause fixes rather than temporary workarounds.

• Shape the future payments architecture. Evolve our systems to support new payment providers, international markets, pricing models, and subscription offerings without compromising reliability.

• Enable other engineering teams. Establish clear interfaces, testing practices, documentation, and engineering standards so Growth and Product teams can safely ship subscription and monetization changes.

• Partner across the business. Work with Finance and Support to improve reconciliation, billing visibility, issue resolution, and the overall learner experience.

• Raise the engineering bar. Mentor engineers, guide architectural decisions, and create lasting improvements in how Speak designs and operates business-critical systems.

What Success Looks Like

In your first 3 months, you'll become the primary engineering owner of Speak's subscription payments infrastructure, understand its most significant reliability risks, and begin addressing critical issues.

Within 6 months, you'll have established meaningful safeguards, monitoring, and engineering practices that proactively detect payment issues and reduce their frequency and impact.

Within 12 months, you'll have transformed payments into a dependable engineering foundation: one that supports international growth, enables faster product development, and operates reliably without constant manual intervention.

What We're Looking For

• Staff-level engineering experience. Typically 10+ years of software engineering experience, with a track record of independently owning complex, business-critical production systems.

• Deep experience with recurring subscriptions. You've personally built, operated, and improved subscription billing systems for a consumer product, including renewals, cancellations, refunds, and failed payments. Experience limited to one-time checkout or payment processing isn't sufficient.

• Consumer mobile payments expertise. You understand subscription billing on the Apple App Store and Google Play, including how purchases, subscription state changes, and entitlements flow through backend systems.

• Experience with subscription payment providers. Hands-on experience with RevenueCat, Paddle, Stripe Billing, or comparable platforms.

• A strong foundation in distributed systems. You're comfortable reasoning about asynchronous events, consistency, retries, idempotency, reconciliation, and failure recovery across multiple systems.

• Strong backend engineering skills. Experience designing and operating reliable backend services and relational databases. Our stack includes Node.js, TypeScript, PostgreSQL, and GCP, but we're open to engineers with strong fundamentals in other technologies.

• A track record of improving reliability. You've identified consequential production risks, investigated incidents, and implemented durable improvements that measurably reduced failures or customer impact.

• High ownership and autonomy. You're comfortable taking responsibility for an unfamiliar or fragmented system, defining priorities without a predefined roadmap, and driving complex improvements from design through production.

• Cross-functional technical leadership. You communicate clearly with engineering and non-engineering stakeholders, make pragmatic tradeoffs, and create systems and practices that help other engineers succeed.

Nice to Have

• Experience migrating between subscription payment providers or consolidating fragmented payment architectures.

• Experience with international subscriptions, including multiple currencies, taxes, payment methods, and regulatory requirements, particularly in APAC markets.

• Experience building or operating shared subscription entitlement systems across mobile and web.

• Experience scaling payments or subscription infrastructure for a consumer application with millions of users.

• Experience as an early or founding engineer for a business-critical technical domain at a high-growth startup.

Why work at Speak

1. 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.

2. 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. We believe in the idea that working with people you both enjoy and have respect for makes everything better. We hire thoughtfully and only work with people we admire deeply.

3. Global in nature: We're live in over 40 countries and launching in a number of new markets soon. We have dedicated offices in San Francisco, Ljubljana, Seoul, Tokyo, and Taipei, and you’ll have the opportunity to talk to users in each of these regions on a regular basis as well as travel.

4. Impact people's lives in a major way: Learning a language is one of the single most life-changing skills one can learn, and right now 99% of people never achieve their goal because the process is broken. We’re helping millions of people achieve their goals and improve their lives.

Speak does not discriminate based upon race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, or other applicable legally protected characteristics.