Staff Software Engineer, Fullstack (Marketing)

<div class="content-intro"><p>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?</p></div><p>Flex is looking for a Staff level Engineer to join our dynamic team and play a pivotal role in accelerating our growth trajectory. In this role, you will be instrumental in developing and scaling the platform and app experiences that empower our users and partners, unlocking our next phase of 10x growth.</p> <p><strong>What You'll Do:</strong></p> <ul> <li>Focus on creating exceptional user and partner experiences that drive engagement and retention.</li> <li>Partner closely with product managers, designers, and data scientists, data analysts to identify and solve critical user onboarding challenges.</li> <li>Design, develop, test, and deploy robust APIs, services and data pipelines that enhance user onboarding and overall platform experience.</li> <li>Implement changes through an agile methodology, prioritizing rapid iteration and continuous improvement.</li> <li>Utilize data and analytics to measure the impact of your work and identify opportunities for optimization.</li> </ul> <h3><strong>Qualifications</strong></h3> <h4><strong>Minimum Qualifications</strong></h4> <ul> <li><strong>7+ years</strong> of professional software development experience.</li> <li><strong>3+ years</strong> of hands-on experience with Java.</li> <li><strong>3+ years</strong> of experience with React or React Native.</li> <li><strong>3+ years</strong> of experience with TypeScript.</li> <li>Having experience building high-quality <strong>mobile and web UIs</strong> to specifications is a <strong>must to have</strong>.</li> <li>Proficient in Java frameworks and tools used at Flex, including Spring (core/web/boot), Gradle, JUnit, and JVM (memory/performance tuning, GC).</li> <li>Experience with Service-Oriented Architecture, REST APIs, Message Queues, and scalable architectures.</li> <li>Experience with architectures and tools in React Native and React ecosystems (Hooks, Components, Conte