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
We are seeking a Staff Software Engineer to join our Money Team, responsible for building and scaling the financial infrastructure that powers payments, billing, subscriptions, payouts, ledgers, and other money movement systems across the company.
As a Staff Engineer, you will provide technical leadership across multiple teams, drive the architecture of mission-critical financial platforms, and help ensure our systems are secure, reliable, compliant, and scalable. You will partner closely with Product, Finance, Risk, Compliance, Data, and Engineering teams to deliver high-impact solutions that directly affect revenue, customer experience, and business operations.
What You’ll Do
- Design, build, and scale backend services and APIs that power Flex's core financial infrastructure, including payments, money movement, billing, settlements, reconciliation, and ledger systems.
- Lead the architecture and evolution of highly available, fault-tolerant financial platforms that process and track millions of dollars in transactions with accuracy, reliability, and auditability.
- Provide technical leadership and guidance on distributed systems design, financial data consistency, transaction integrity, and long-term platform strategy.
- Drive the delivery of highly impactful initiatives end-to-end, from requirements gathering and technical design through implementation, rollout, and operational excellence.
- Partner closely with Product, Finance, Risk, Compliance, Operations, and cross-functional engineering teams to deliver scalable and compliant payment experiences.
- Build robust systems that integrate with external payment processors, banking partners, card networks, and financial service providers.
- Design and implement resilient ledger, settlement, and reconciliation workflows that ensure financial accuracy across the ecosystem.
- Drive adoption of engineering best practices across the organization, including observability, automated testing, reliability engineering, CI/CD, and secure software development.
- Mentor and support engineers on the team, raising the technical bar and fostering a culture of technical excellence and ownership.
- Operate mission-critical financial services in production with stringent uptime, security, compliance, and performance requirements.
- Contribute to the evolution of Flex's service-oriented architecture, event-driven systems, APIs, message queues, and scalable financial platforms.
- Balance hands-on execution with architectural leadership, ensuring both rapid delivery and long-term maintainability of critical money movement systems.
Who You Are
- 6–8+ years of professional software engineering experience, with a focus on backend development.
- 4+ years of hands-on Java experience (Spring core/web/boot, Gradle, JUnit, JVM tuning & performance).
- Strong computer science fundamentals and proven experience designing scalable, distributed systems.
- Deep experience building or operating financial systems, including payments, money movement, ledgers, settlements, reconciliation, billing, or banking infrastructure.
- Experience integrating with payment processors, settlement, card networks, banking partners.
- Strong understanding of transactional systems, financial data consistency, idempotency, auditability, and fault tolerance in distributed environments.
- Skilled at working with both technical and non-technical stakeholders, aligning on scope and delivery.
- Ability to write high-quality, testable, maintainable, and secure code.
- Hands-on experience with AWS (EKS, Aurora RDS, Elasticache, DynamoDB), containerization (Docker/Kubernetes), and relational + NoSQL databases (MySQL, PostgreSQL, DynamoDB).
- Proficient with CI/CD pipelines (GitHub Actions preferred), git, and build automation.
- Familiar with observability and monitoring tools (e.g., DataDog) for maintaining service availability.
- Excellent communicator, comfortable collaborating in globally distributed teams.
- Track record of mentoring engineers and raising team standards through best practices.
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.
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
Skills Required
- 6-8+ years professional software engineering experience focused on backend development
- 4+ years hands-on Java experience (Spring core/web/boot, Gradle, JUnit, JVM tuning & performance)
- Strong computer science fundamentals and experience designing scalable, distributed systems
- Deep experience building or operating financial systems: payments, money movement, ledgers, settlements, reconciliation, billing, or banking infrastructure
- Experience integrating with payment processors, settlement systems, card networks, and banking partners
- Strong understanding of transactional systems, data consistency, idempotency, auditability, and fault tolerance
- Hands-on experience with AWS (EKS, Aurora RDS, Elasticache, DynamoDB)
- Containerization and orchestration: Docker and Kubernetes
- Experience with relational and NoSQL databases (MySQL, PostgreSQL, DynamoDB)
- Proficient with CI/CD pipelines and build automation (GitHub Actions preferred), and git
- Familiarity with observability and monitoring tools (e.g., DataDog)
- Excellent communication skills and ability to collaborate with technical and non-technical stakeholders
- Track record of mentoring engineers and raising technical standards
- Ability to write high-quality, testable, maintainable, and secure code
Flex Compensation & Benefits Highlights
The following summarizes recurring compensation and benefits themes identified from responses generated by popular LLMs to common candidate questions about Flex and has not been reviewed or approved by Flex.
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Healthcare Strength — Day-1 medical, dental, and vision coverage is explicitly offered and framed as “best-in-class coverage and options,” suggesting strong baseline health benefits. Additional listings also describe broad health-support elements such as IVF/adoption and gender transition benefits, reinforcing depth in healthcare-related coverage.
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Retirement Support — A 401(k) is available, with a stated company match starting in early 2026, indicating improving retirement support. This rollout appears to address earlier gaps where matching was not consistently present.
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Leave & Time Off Breadth — Unlimited PTO plus company holidays (and, in some descriptions, shutdown days) indicates a wide time-off policy on paper. Hybrid work flexibility and office-day meal credits can add to the overall rewards value for NYC-based employees.
Flex Insights
What We Do
Flex, an NYC-headquartered FinTech company, has created a trusted rent payment experience. It’s hard to believe that it’s 2024 and paying rent on time is expensive, inflexible, and difficult; we’re here to change that! We enable our users to pay rent throughout the month on a schedule that better fits their finances and budget, while also helping them build credit. Our mission is to empower as many renters as possible with flexibility over their most significant recurring expense.
Why Work With Us
We believe it takes a diverse team of curious, determined, empathetic, and self aware people to grow a successful company. We value the unique and dynamic perspectives our team brings to solve critical problems that impact the lives of our users and the financial decisions they make.
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