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Staff Software Engineer, Consumer (Full Stack)

New York, New York, United States

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

Flex is looking for a Staff Software Engineer who will be responsible for developing and enhancing end-user experiences across our mobile and web platforms.

In this role you will be working closely with your team to launch new features. You’ll be developing, designing, testing, and scaling new product offerings that solve complex problems in a simple way for all of our users. As a staff engineer, you will play a key role in defining solutions, breaking down scope into actionable plans and leading your cross-functional team through implementation.

You can expect to be working closely with other cross functional partners across our organization on a daily basis. Our team works in an agile manner, and some of the partners you can expect to work with in this role include designers, product managers, and quality engineers. We expect you to be able to be hands-on and execute on work as both an individual, while also building products that allow for flexibility as we are evolving our product offerings.

This is a hybrid position with on-site expectations of 3 days per week in our New York Headquarters (Union Square). For candidates outside of the NY/NJ area, you may be eligible for our relocation assistance program.

What you’ll do

  • You’ll work closely with your product, design and engineering peers to solve our users' most pressing problems around rent payment. 
  • You’ll provide guidance on the long-term vision and architecture of our application stack, ensuring best practices and consistency across the team.
  • You’ll roll out changes to our customers in an agile manner with a delivery cadence that favors small, frequent iterations.  
  • You’ll lead by example making high impact contributions, mentoring others and fostering a high performance culture.
  • The ideal candidate will be comfortable leading scoping, design and implementation for product features they build and can drive their production rollouts to completion with minimum oversight.

Key qualifications

Skills that are required: 

  • Strong computer science fundamentals 
  • Mobile & Web Development
    • Proficiency in React.js/React Native (7+ years) and associated tools (Hooks, Context, Redux).
    • Experience building high-quality, scalable mobile and web UIs.
    • Strong TypeScript development skills, with a focus on maintainability and documentation.
    • Familiar with iOS/Android/web development tool ecosystems (Bonus: Native iOS/Android experience).
  • API Development
    • Proficiency in Java (5+ years) and Spring Framework (Core/Web/Boot).
    • Experience building and maintaining high-quality APIs at scale.
    • Strong understanding of REST API design and mobile API best practices.
    • Experience with distributed services architecture, observability, and monitoring tools (e.g., DataDog).
    • Ability to write maintainable, testable code with best practices in unit testing, linting, and automation.
  • Collaboration & Mentorship
    • Proven ability to mentor engineers and promote software development best practices.
    • Strong communication skills and experience working with distributed teams.

Core competencies: 

  • Experience working on cross-functional teams involving product, design, and engineering.
  • Proficient in Java (Spring Boot), TypeScript (React.js/React Native).
  • Familiar with CI/CD pipelines to improve code stability and quality.
  • Experience with cloud and containerized environments (Bonus: AWS, Kubernetes, MySQL).
  • Comfortable working with IDEs such as VSCode, IntelliJ, XCode, and Android Studio.
  • Motivated to drive team effectiveness and engineering excellence.

The compensation range for this role will be commensurate with the candidate's experience and Flex's internal leveling guidelines and benchmarks.

  • For working locations in NY/NJ/CA, the base salary pay range will be $221,000-$237,000

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.

We offer many employee benefits. For full time, U.S. based employees we offer:

  • Competitive pay
  • 100% company-paid medical, dental, and vision
  • 401(k) + company equity
  • Unlimited paid time off with a PTO minimum + 13 company paid holidays
  • Parental leave 
  • Flex Cares Program: Non-profit company match + pet adoption coverage
  • Free Flex subscription

 For full time non-US employees, we offer

  • Competitive Pay
  • Company Equity
  • Unlimited PTO

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