Sr Backend engineer

About the Client We exist to help people live healthier lives and save money while they do it. We’re building the first HSA/FSA that actually works for modern life by letting people spend pre-tax dollars on everyday wellness like the gym, recovery, and prevention. Founded by repeat healthcare founders, we’re backed by a16z Speedrun, Opal Ventures, and founders from companies like Thirty Madison, Clay, and Papa. About The Role We’re looking for a product-minded backend engineer to help us build the financial and data infrastructure powering our product. This is a high-ownership role working on systems at the intersection of payments, healthcare, and consumer products. You’ll make foundational decisions on architecture, data models, and how we handle sensitive financial and health information. Today, we’re a very small team building quickly. The focus right now is on building things well and shipping fast, not on management. That said, this role can evolve over time as the team grows.

Responsabilidades

• Design and build core backend systems across payments, ledgers, and health eligibility
• Own architectural decisions around data integrity, fault tolerance, and security
• Build reliable integrations with external providers and APIs
• Work closely with product and design to ship quickly without sacrificing quality
• Use AI coding tools and build agentic workflows to automate development and produce well-tested, elegant code quickly
• What we are looking for
• Strong experience in backend systems, ideally in payments, fintech, or healthcare.
• Experience with providers like Stripe, Plaid, or similar ecosystems
• Strong understanding of relational and transactional data systems (consistency, atomicity, concurrency, locking)
• Comfort making high-impact architectural decisions with minimal oversight
• A builder mindset with a bias toward shipping and iteration
• Deep familiarity with AI coding tools and interest in building agentic workflows that generate well-tested, maintainable code with faster iteration cycles
• Strong communication skills: clear writing, responsiveness, and willingness to engage directly with external partners

Requisitos

• TypeScript across the stack
• Next.js (web), Expo / React Native (mobile)
• Postgres as our core data layer
• Railway (infrastructure), Datadog (logging), PostHog (analytics)
• We prioritize simple, well-understood systems:
• Functional programming patterns
• Immutability where it matters
• Systems designed for fault tolerance, security, and maintainability

Deseable

• Why This Role
• Help transform a healthcare system that is unnecessarily complex and expensive today into one that is simpler, more accessible, and more affordable
• Build foundational systems in a fast-moving, high-context team
• Be early enough to shape both the product and the engineering culture