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 job Flex is looking for a Software Engineer who will be responsible for implementing the various backend systems that support all business features. In this role, you will be part of the backend engineer team, responsible for the services and integrations that power our products, such as Payment, Billing, Identity, partner integration, etc. You’ll be designing, developing, testing, and scaling systems needed to deliver great user and partner experiences. You’ll work closely with your product, design and engineering peers to solve our users' most pressing problems around rent payment. You’ll roll out changes to our customers in an agile manner with a delivery cadence that favors small, frequent iterations. The ideal candidate will be comfortable leading scoping, design and implementation for APIs they build and can drive their production rollouts to completion with minimum oversight. A minimum of 4 years of experience with Java is required for this position. Minimum Qualifications Minimum of 6 years experience in software engineering Minimum of 4 years experience with Java 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 Ability to grow in a fast-paced and dynamic environment that will challenge you to always bring your best 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. Skilled at elevating team standards through best practices, and mentoring junior engineers. Excellent written and verbal communicator, with experience in cross-functional collaboration. 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/SF/Seattle): $172,000—$212,000 USD Tier 2: $154,800—$193,500USD Tier 3: $146,200—$182,740 USD #LI-Remote 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