Senior Backend Engineer — Payments & Money Movement

Flex; United States; Hybrid; USD 146,000 - 183,000; Full time

Benefits offered by this job

Competitive medical, dental, andvision

Company equity

401(k) with company match

Unlimited PTO and holidays

Parental leave

Job summary

Flex, a NYC-based FinTech, seeks a Senior Software Engineer to join the Money Team, building and scaling the financial infrastructure powering payments, billing, and money movement. You will lead technical direction across teams, ensuring secure, reliable, and scalable systems that impact revenue and customer experience.

You will partner with Product, Finance, Risk, Compliance, Data, and Engineering to deliver high-impact solutions, with hybrid work options across NY, SF, and Salt Lake City.

Qualifications

• 5+ years of software engineering experience with Java backend, Spring framework, Gradle, and JVM tuning.
• Experience integrating with payment processors, settlements, billing, and money movement systems.
• Strong fundamentals in distributed systems, data consistency, idempotency, and fault tolerance.

Responsibilities

• Design, build, and scale backend services and APIs powering core financial infrastructure.
• Lead end-to-end initiatives from requirements to rollout and operational excellence.
• Collaborate with Product, Finance, Risk, Compliance, Operations and other engineering teams to deliver scalable payment experiences.
• Build robust systems integrating with external payment processors, banking partners, and card networks.
• Design and implement resilient payment, ledger, settlement, and reconciliation workflows.
• Operate mission-critical financial services in production with uptime, security, and performance.
• Contribute to service-oriented architecture, event-driven systems, APIs, queues, and scalable platforms.

Skills

Java backend

Distributed systems

AWS

CI/CD

Observability

Communication

Tools

Docker

Kubernetes

MySQL

PostgreSQL

DynamoDB

GitHub Actions

Job description

Flex, a NYC-based FinTech, seeks a Senior Software Engineer to join the Money Team, building and scaling the financial infrastructure powering payments, billing, and money movement. You will lead technical direction across teams, ensuring secure, reliable, and scalable systems that impact revenue and customer experience.

You will partner with Product, Finance, Risk, Compliance, Data, and Engineering to deliver high-impact solutions, with hybrid work options across NY, SF, and Salt Lake City.