Senior Full-Stack Software Engineer (Backend-Focused)

About Paytient: We’re on a mission to help people better access and afford care. Every day, millions of people, and their loved ones, need to see a doctor. For most of us, that moment is an uncertain one - we’re unsure of what’s wrong, who to go to, how long it’ll take to be seen, when we’ll feel better, and what it’ll cost.Paytient partners with thoughtful employers and health plans who understand the impact of that moment and want to ensure that every one of their plan members are easily able to access and afford care. Our clients understand that an improved ability to self-pay for care changes patient behavior and creates value for the health plan. This founding belief is becoming an emerging standard of care in health plan design and is now, in fact, a mandatory capability in some governmental health plans. Founded in 2018, Paytient is now part of nearly 6,000 employer health plans and providing certainty that people are better able to access and afford care.We’re looking for passionate, collaborative builders to join our team and help us create a future where everyone can more easily access and afford care. About The Role: We're actively recruiting for a Senior Full-Stack Engineer who is motivated by solving big challenges and passionate about working closely with product managers, designers, and other engineers to build elegant software. If you're excited about working at a high-growth, venture-backed company and want to make an impact by building products that help people, we'd love to hear from you!In this role, you'll work primarily on the backend while contributing across the full stack, including frontend (React/React Native) and backend (Java/Spring Boot + Kotlin) applications. Deep backend expertise is essential, while frontend experience is a plus - we'll look to you to own complex server-side systems and collaborate on frontend as needed. This position is on our Growth & Core Ops Product Engineering team, where we build the foundational systems that power our business. As an Engineer on this team, you'll solve complex, high-stakes backend challenges, from automating intricate payroll deductions and ensuring the integrity of member census data, to transforming manual processes into elegant, automated workflows for invoicing, subscription management, and financial reporting.Our "remote with roots" model allows us to work where we thrive and gather as needed, often in our home office in Columbia, Missouri. This role can be performed from anywhere in the continental U.S., with the exception of Montana.What You'll Do:Collaborate with product managers, designers, and engineers to build scalable, reliable backend systems that power our core financial and data ecosystems, with frontend contributions as needed.Lead backend development using Java/Spring Boot or Kotlin to build robust systems for payroll deductions, payment processing, and automated invoicing, while contributing to our React frontend when the work requires it.Write clean, maintainable, and well-tested backend code that balances performance with the high level of accuracy required for census data management and subscription billing.Lead initiatives and own complex backend projects, such as architecting seamless payment integrations or scaling our subscription management engine, from concept through delivery.Influence backend architectural decisions and contribute to a long-term technical strategy that ensures data integrity across our payroll and financial reporting pipelines.Drive engineering excellence by authoring clear technical documentation, including RFCs and ADRs for new architectural patterns, and maintaining up-to-date runbooks to ensure our systems remain reliable and easy to operate.Leverage AI assisted development tools to accelerate delivery, optimize workflows, and enhance code quality, while maintaining a critical eye for security and best practices.Participate in code reviews and technical discussions, ensuring our systems handle complex business logic (like deduction calculations) with precision and security.Provide technical mentorship and guidance to other engineers, fostering a culture of excellence in healthcare and financial engineering.Work in a modern, cloud-native environment leveraging infrastructure-as-code and CI/CD pipelines to support rapid, high-quality delivery of mission-critical financial features.What You'll Bring:5+ years of professional experience with a proven track record of technical impact and leadership, with a strong emphasis on backend systems.Strong problem-solving skills, curiosity, and the ability to navigate complex challenges in high-stakes financial environments.Deep experience with Java, Spring Boot, or Kotlin is required - this is the core of what you'll do. Experience with or interest in React for occasional fullstack contributions is a plus.An AI-forward mindset, with experience using AI assisted development tools (like GitHub Copilot, Claude Code, or OpenCode) to streamline workfl