Staff 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 Our Opportunities Flex exists to make paying rent work the way real life actually works — smoothing out cash flow, helping renters avoid late fees, and letting them build credit instead of falling behind. As a Staff Backend Engineer, you'll design, build, and scale the services and integrations behind Payment, Billing, Identity, and partner integrations that keep rent moving on time for renters every month — setting the long-term technical vision and architecture for the systems you own, leading scoping, design, and implementation across teams, driving your own production rollouts to completion with minimal oversight, and working closely with product, design, and engineering peers to solve renters' most pressing problems in small, frequent iterations rather than big, risky releases. You'll also raise the bar for the engineers around you, mentoring peers and driving consistency and best practices across the org. About Our Team(s) We have some really exciting teams who are looking for an amazing engineer like you! Check them out! • Partner Integrations - Partner integrations work to standardize APIs, tools, and processes that let external partners connect to Flex for data sharing and payments across entry points like Flex Anywhere and Quick-Pay • Money Team - builds and owns the platforms, tooling, and documentation powering Flex's payments, wallet, and settlement finance systems. Who thrives here? • A Doer — you get things done efficiently, and you're comfortable rolling up your sleeves when something's blocking the team. • An Owner — you take full accountability for what you build, from design through production, and you always have a plan B. • Someone Collaborative — you bring people together to pressure-test ideas rather than working in a silo. • Someone with Precision — your code and your communication are both clear, because ideas only matter once others can act on them. • Someone Resilient — systems break and priorities shift, and you adapt without losing momentum. • Someone Humble — you care more about getting to the right answer than being the one who's right. Qualifications Minimum Qualifications • Minimum of 8 years experience in software engineering • Minimum of 6 years experience with Java • Proven ability to set technical direction and architecture for complex, distributed systems • Ability to lead and mentor engineers, raising the technical bar across a team or org • Ability to work on a globally-distributed team with a high degree of ownership • Experience working with technical and non-technical stakeholders, successfully aligning and setting expectations on scope and delivery • Experience building robust, fault-tolerant systems with multiple external dependencies • Experience designing, building, and maintaining data pipelines • 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 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 • Track record of elevating team standards through best practices, and mentoring engineers at all levels • Excellent written and verbal communicator, with experience influencing cross-functional strategy Compensation 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 1 (NYC/Bay Area, Los Angeles, Seattle) $200,000—$250,000 USD Tier 2 (Austin, Washington D.C. Philadelphia, San Diego, Chicago, Atlanta) $180,000—$225,000 USD Tier 3 (Salt Lake City, all other USA cities) $170,000—$212,500 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 • Free Flex subscription For full-time non-U.S. employees, we offer: • Competitive compensation + company equity • Unlimited PTO