Senior Software Engineer, Fullstack at Flex

This role is ideal for a seasoned Fullstack Engineer with a strong foundation in **Java** and **React Native**. If you have at least 5 years of professional exp

Work type: remote

Location: New York, New York, United States; Remote; San Francisco, California, United States

Salary: $172,000 – $210,000/yr

Type: Full-time

Summary

This role is ideal for a seasoned Fullstack Engineer with a strong foundation in **Java** and **React Native**. If you have at least 5 years of professional experience and a background in FinTech or growth-stage startups, you’ll fit right in. The team is specifically looking for someone who can bridge the gap between robust backend services (Spring Boot) and polished mobile/web interfaces. The position offers a highly competitive salary range up to **$210,000**, with fully remote flexibility across the US. As a growth-stage company, this is an opportunity to scale a product that directly impacts people's financial health. Standout perks include **Day 1 medical benefits**, company equity, and a 401(k) match starting in 2026. **You might be a good fit if you:** * Have 3+ years of hands-on experience with **Java (Spring)** and **React Native**. * Enjoy working on "Growth" initiatives like optimizing user onboarding funnels. * Are comfortable navigating AWS environments (EKS, Aurora, DynamoDB). * Thrive in agile environments where you iterate quickly based on data and analytics.

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?

Flex is looking for an Engineer to join our dynamic team and play a pivotal role in accelerating our growth trajectory. In this role, you will be instrumental in developing and scaling the platform and app experiences that empower our users and partners, unlocking our next phase of 10x growth.

What You'll Do:

• Focus on creating exceptional user and partner experiences that drive engagement and retention.

• Partner closely with product managers, designers, and data scientists, data analysts to identify and solve critical user onboarding challenges.

• Design, develop, test, and deploy robust APIs, services and data pipelines that enhance user onboarding and overall platform experience.

• Implement changes through an agile methodology, prioritizing rapid iteration and continuous improvement.

• Utilize data and analytics to measure the impact of your work and identify opportunities for optimization.

#### Minimum Qualifications

• 5+ years of professional software development experience.

• 3+ years of hands-on experience with Java.

• 3+ years of experience with React or React Native.

• 3+ years of experience with TypeScript.

• Having experience building high-quality mobile and web UIs to specifications is a must to have.

• Proficient in Java frameworks and tools used at Flex, including Spring (core/web/boot), Gradle, JUnit, and JVM (memory/performance tuning, GC).

• Experience with Service-Oriented Architecture, REST APIs, Message Queues, and scalable architectures.

• Experience with architectures and tools in React Native and React ecosystems (Hooks, Components, Context, Redux).

• Experience with AWS (EKS, Aurora RDS, Elasticache, DynamoDB) and containerization tools.

• Have the experience to build and improve user onboarding funnel and design the comprehensive experiment to drive metric improvements.

• Proficient in CI/CD systems (preferably GitHub Actions), git, and automation.

• Skilled in observability and monitoring tools, such as DataDog, to ensure high availability.

• Experienced with big data platforms and tooling, including Snowflake.

• Proficient in Infrastructure as Code, using tools like CDK and Terraform.

• Skilled at elevating team standards through best practices, and mentoring junior engineers.

• Excellent written and verbal communicator, with experience in cross-functional collaboration.

• Tier A (NYC/SF/Seattle): $172,000—$210,000 USD

• Tier B: $154,000—$190,000 USD

• Tier C: $146,000—$180,000 USD

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

• Flex Cares Program: Non-profit company match + pet adoption coverage

• Free Flex subscription

• Competitive compensation + company equity

• Unlimited PTO

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