Senior Software Engineer, Fullstack (Risk Engineering)

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 looking for a Senior Software Engineer to join our Risk Engineering team. This role involves spearheading the implementation of platforms and APIs crucial for supporting business features within the risk management domain. The Risk Engineering team is dedicated to mitigating both credit risk, fraud risk, and risk for launching new products. Our mission is to enhance Flex app accessibility for customers while safeguarding against improper use and unauthorized access by identifying and preventing misuse across all core product areas. Following are some projects/systems in Risk Platform you will have opportunities to work with: Core decision platform which is an end [... source excerpt omitted ...] lytics, process management, and ML/AI. Event data stream ingestion which supports near real-time fraud rules setup. Advanced a/b testing and experimentation capabilities for our customers so they can leverage greedy algorithms and fight fraud. What You'll Do: Build decision platform / machine learning solutions to respond to/mitigate business risks in Flex. Design and develop 24/7 high-scale APIs and distributed systems. The tech stack will be on AWS. Java would be the language for the existing code base. Java Spring Boot will be the framework. Work closely with product, design, and engineering peers to launch new features across our web and mobile platforms Qualifications [... source excerpt omitted ...] ools in React Native and React ecosystems (Hooks, Components, Context, Redux). Experience with AWS (EKS, Aurora RDS, Elasticache, DynamoDB) and containerization tools. Preferred Qualifications Proficient in CI/CD systems (preferably GitHub Actions), git, and automation. Skilled in observability and monitoring tools, such as DataDog, to ensure high availability. Experienced with big data platforms and tooling, including Snowflake. Proficient in Infrastructure as Code, using tools like CDK and Terraform. Skilled at elevating team standards through best practices, and mentoring junior engineers. Excellent written and verbal communicator, with experience in cross-functional collabo