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-to-end solution for the enterprise decision management lifecycle, including business rule management, analytics, 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

Minimum Qualifications

• Must-have: Experience working in a risk engineering team, specializing in rules engine architecture or risk/credit/fraud systems.

• 6+ years of professional software development experience.

• 5+ years of hands-on experience with Java.

• 2+ years of experience with React or React Native.

• 2+ years of experience with TypeScript.

• Having experience building high-quality mobile and web UIs to specifications is a must to have.

• Proficient in Java frameworks and tools used at Flex, including Spring (core/web/boot), Gradle, JUnit, and JVM (memory/performance tuning, GC).

• Experience with Service-Oriented Architecture, REST APIs, Message Queues, and scalable architectures.

• Experience with architectures and tools 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

Flex takes a market-based approach to pay, and compensation may vary depending on your primary work location. Work locations are categorized into one of three tiers based on a cost of labor index for that geographic area. The successful candidate’s starting pay will be commensurate with their experience, qualifications, and Flex’s internal leveling guidelines and benchmarks.

• Tier A (NYC/SF/Seattle): $172,000—$210,000 USD

• Tier B: $154,000—$190,000 USD

• Tier C: $146,000—$180,000 USD

Life at Flex

We understand that it takes a diverse team of highly intelligent, curious, determined, empathetic, and self aware people to grow a successful company. Our HQ is located in New York City, but we have employees located throughout the US, Australia, Canada and South America. We are growing quickly, but deliberately, with a focus on building an inclusive culture. Our dynamic team has incredible perspectives to share, just as we know you do, and we take great pride in being an equal opportunity workplace.

Offices

Roles posted in New York, San Francisco, and Salt Lake City are hybrid positions with on-site expectations of 2-3 days per week in our local offices. For candidates outside of these areas, you may be eligible for our relocation assistance program.

Benefits

For full-time U.S. employees we offer:

• Competitive medical, dental, and vision

• Company equity

• 401(k) plan with company match

• Unlimited paid time off + 13 company paid holidays

• Parental leave

• Flex Cares Program: Non-profit company match + pet adoption coverage

• Free Flex subscription

For full-time non-U.S. employees, we offer:

• Competitive compensation + company equity

• Unlimited PTO