Staff Software Engineer, FinPlatform Backend

Flex is a growth-stage, NYC headquartered FinTech company that is creating the best rent payment experience. It’s hard to believe that it’s 2026 and paying rent on time is expensive, inflexible, and difficult. We’re here to change that! Flex enables our users to pay rent throughout the month on a schedule that better fits their finances and budget. Our mission is to empower as many renters as possible with flexibility over their most significant recurring expense. After deliberately keeping a stealth profile as we built up unprecedented investor support and an enthusiastic user base, we are looking for motivated individuals to help us keep our mission growing. Will you be a part of the team? Overview Flex is a growth-stage, NYC headquartered FinTech company that is creating the best rent payment experience. It’s hard to believe that it’s 2026 and paying rent on time is expensive, inflexible, and difficult. We’re here to change that! Flex enables our users to pay rent throughout the month on a schedule that better fits their finances and budget. Our mission is to empower as many renters as possible with flexibility over their most significant recurring expense. After deliberately keeping a stealth profile as we built up unprecedented investor support and an enthusiastic user base, we are looking for motivated individuals to help us keep our mission growing. Will you be a part [... source excerpt omitted ...] As a Staff Engineer at Flex, you’ll help set technical direction and shape the long-term architecture of our backend services while still being hands-on with coding and delivery. You will collaborate across engineering, product, design, and other stakeholders to ensure scalable, reliable, and impactful systems that power consumer experiences, partner integrations, and our core business platforms. You’ll also play a critical role in mentoring engineers, elevating technical standards, and ensuring the success of projects end-to-end. Our Engineering Teams Consumer Engineering: Builds the APIs and backend systems powering Flex’s main consumer-facing products. This team focuses on [... source excerpt omitted ...] Partner Integrations, ensuring Flex’s foundation is robust and scalable. Risk Platform Engineering: Develops the platforms and APIs that mitigate credit and fraud risk, enhancing customer accessibility while safeguarding against misuse through advanced rules engines, machine learning, and event data systems. What You’ll Do Design, implement and maintain our Finance service and internal tooling, including financial reporting, reconciliation/audit process. Design and develop new APIs and functionalities to support large money movements across our banking partners via different payment rails, such ACH. Scale out core platform to support business growth while maintaining perform