Senior Software Engineer, 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? About the Role Flex is hiring a Senior Engineer to join our backend engineering team, where you'll be responsible for designing, building, and scaling the systems that power our core products — including Payments, Billing, Identity, and partner integrations. You'll work on services that directly shape how hundreds of thousands of renters experience financial flexibility, and your work will have a measurable impact on the reliability and performance of everything we ship. In this role, you'll own meaningful portions of our backend infrastructure end-to-end — from scoping and API design through production rollout — with the autonomy to make independent technical decisions that drive real customer and business impact. You'll collaborate closely with product, design, and engineering peers in