Senior Software Engineer - Partner Integrations

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 Partner Engineering organization and help build out our payment integrations platform & user experiences. As a part of our Partner Engineering organization, you will be responsible for the backend systems and services that manage our most important external integrations & power our product. You will work with teams across the organization including Engineering, Product, Design, Infrastructure, Sales, Partner and Customer Success to deliver products that wow our customers partners alike. We expect you to be hands-on and execute work as an individual, and build products that allow for flexibility as we evolve our product offerings. 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. 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) $172,000—$215,000 USD Tier 2 (Austin, Washington D.C. Philadelphia, San Diego, Chicago, Atlanta) $154,800—$193,500 USD Tier 3 (Salt Lake City, all other USA cities) $146,200—$182,750 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