Staff Software Engineer, FinPlatform Backend

About the role

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? Flex is looking for a Staff Software Engineer to join our core platform team. We want engineers with ideas (because they'll definitely be heard on our small and tight-knit team) and ambition! Successful devs will feel comfortable in a startup environment and will be happy to work in a remote-first team with a lot of independence. As a Staff Engineer at Flex, you'll help set technical direction and shape the long-term architecture of our backend services while still being hands-on with coding and delivery. You will collaborate across engineering, product, design, and other stakeholders to ensure scalable, reliable, and impactful systems that power consumer experiences, partner integrations, and our core business platforms. You'll also play a critical role in mentoring engineers, elevating technical standards, and ensuring the success of projects end-to-end. Our Engineering Teams Consumer Engineering: Builds the APIs and backend systems powering Flex's main consumer-facing products. This team focuses on delivering scalable services for a seamless rent payment experience through our mobile and web apps. Partner Integrations Engineering: Owns the backend services and integrations that connect Flex to financial partners and payment networks, ensuring reliable, secure payment flows and partner-facing experiences. Core Platform Engineering: Maintains the backend systems and infrastructure supporting all business features, including Payments, Billing, Identity, and Partner Integrations, ensuring Flex's foundation is robust and scalable. Risk Platform Engineering: Develops the platforms and APIs that mitigate credit and fraud risk, enhancing customer accessibility while safeguarding against misuse through advanced rules engines, machine learning, and event data systems.

Responsibilities

• Design, implement and maintain our Finance service and internal tooling, including financial reporting, reconciliation/audit process.
• Design and develop new APIs and functionalities to support large money movements across our banking partners via different payment rails, such ACH.
• Scale out core platform to support business growth while maintaining performance and reliability
• Continuously improving our daily operations with automation, tooling, design evolution, observability etc.
• Work closely with product, analytics, finance and engineering peers to launch new financial features into our platform

Requirements

• 6+ years of experience in software development or a related field
• Experience in technical leadership, guiding engineering teams through complex projects
• Experience with Java, Python, Golang, or TypeScript/Node.js.
• Strong experience with relational SQL and NoSQL databases, such as MySQL/PostgreSQL/DynamoDB
• Experience in designing and developing the fault-tolerant and scalable distributed systems
• Experience with AWS cloud services: ESC/EKS, Lambda, API Gateway, VPN, RDS etc
• Infrastructure as code(AWS CLI, AWS CDK/Terraform)
• Strong communication skills with the ability to understand and explain technical issues to a non-technical audience
• Follow engineering best practices as well as propose new ones
• Experience with finance reporting and reconciliation
• Deep experience with writing complex query and data mining
• #LI-Remote

Benefits

Additional Information

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?

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