Staff Software Engineer, Partner Integrations

Flex

4d•$170,000 - $250,000•Hybrid

About The Position

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? As we continue to grow our talented team, we remain committed to radical transparency, integrity, and individual growth. We believe that your unique background and experience adds tremendous value to the organization and will empower you to take absolute ownership of business challenges and the execution of solutions.

Requirements

Minimum 6 years of experience in software engineering
Minimum 4 years of experience with Java; proficient in Spring (core/web/boot), Gradle, JUnit, and JVM tuning
Experience with Service-Oriented Architecture, REST APIs, message queues, and scalable distributed systems
Experience with AWS (EKS, Aurora RDS, Elasticache, DynamoDB) and containerization
Experience leading delivery of multiple high-impact products end to end, on time with a high quality bar
Ability to work on a globally-distributed team with a high degree of ownership
Experience aligning technical and non-technical stakeholders on scope and delivery
Experience in FinTech and familiarity with major payment rails
Ability to drive quality and consistency across your team without compromising velocity

Nice To Haves

Proficient in CI/CD systems (preferably GitHub Actions) and automation
Skilled in observability and monitoring tools such as DataDog
Experienced with big data platforms including Snowflake
Proficient in Infrastructure as Code (CDK, Terraform)
Excellent written and verbal communicator with cross-functional collaboration experience

Responsibilities

Design, implement, and maintain our payment integrations platform, including partner APIs, SDKs, and embedded web experiences
Help shape and drive the technical roadmap for the Partner Engineering team
Design and develop scalable APIs and integrations to support money movements across our banking partners via payment rails such as ACH
Work cross-functionally with Engineering, Product, Design, Infrastructure, Sales, Partner, and Customer Success to deliver high-impact features
Scale our integrations platform to support business growth while maintaining performance and reliability
Continuously improve daily operations through automation, tooling, design evolution, and observability
Mentor engineers and elevate team standards through best practices, code reviews, and technical guidance