Role overview

Qualifications

5+ years of professional software engineering experience, with a focus on Java backend development
Strong computer science fundamentals and proven experience designing scalable, distributed systems
Experience integrating with payment processors, settlement, card networks, banking partners
Ability to write high-quality, testable, maintainable, and secure code

Responsibilities

Design, build, and scale backend services and APIs that power Flex's core financial infrastructure
Drive the delivery of highly impactful initiatives end-to-end, from requirements gathering to operational excellence
Partner closely with cross-functional teams to deliver scalable and compliant payment experiences
Operate mission-critical financial services in production with stringent uptime, security, compliance, and performance requirements

Key facts

Full time
Senior (5-10 years)
Back-End Developer
183 - 215K yearly
English

Hard skills

Java (Programming Language) Back End (Software Engineering) Amazon Web Services Gradle Junit Java Virtual Machine (JVM) Distributed Computing Payment Service Provider Banking CI/CD Kubernetes MySQL PostgreSQL Amazon DynamoDB Datadog

Other skills

Communication
Collaboration

About the company

Flex

Buy Now Pay Later (BNPL) & Consumer Credit

Flex is a simple app that’s changing the way the world pays and collects rent. Our technology makes the 1st of the month easy for renters and properties. For renters, we pay the rent on the 1st and let you pay it back when it works better for your budget. We help you buy some time (or whatever else you’re eyeing). For properties, we help you collect more and stress less. And we do the previously impossible by turning rent collection into a marketable amenity. WHAT WE STAND FOR •We believe you should be able to choose when you pay your bills. The flexibility of buy-now-pay-later has forever changed the way the world makes purchases. We believe the same flexibility should be available for one of life’s #1 expenses: rent. •We believe in the win-win. We like helping people keep commitments. With our technology, properties get the rent and renters get the time. The future is flexible. •We believe in the end of rent regret. Sharing human spaces used to be easier. But then payment came into the picture and rent regret was born. The worst part of rent regret is that it separates us from each other. We’re committed to solving rent regret forever.

Company details

Company typeScaleup

IndustryBuy Now Pay Later (BNPL) & Consumer Credit

Company size201 - 500

Links

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Job description

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 a growth-stage, NYC headquartered FinTech company that is creating the best rent payment experience. It’s hard to believe that it’s 2025 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 Senior 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 Senior 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.
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 payment, ledger, settlement, and reconciliation workflows that ensure financial accuracy across the ecosystem.
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.

Who You Are

5+ years of professional software engineering experience, with a focus on Java backend development(Spring core/web/boot, Gradle, JUnit, JVM tuning & performance).
Strong computer science fundamentals and proven experience designing scalable, distributed systems.
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.

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