Job Description -Senior Staff Decision Scientist

Overview 

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?

About the role

As a Senior Staff Decision Scientist on the Risk & Decision Science team, you’ll own the strategy and optimization of Flex’s payment decisioning stack. This includes authorization optimization, PSP routing, retries/failover logic, and cost vs. risk tradeoffs across millions of dollars of payment volume.

This is a high-impact, senior individual contributor role where you’ll work at the intersection of payments, product, engineering, finance, and data to improve core platform economics and customer experience.

If you’ve worked on payments platforms, risk systems, credit, or large-scale decisioning at companies like Stripe, PayPal, Square, Adyen, Affirm, or big tech, this role is very much in that vein.

What you’ll do

• Own and evolve Flex’s payment decisioning and routing strategy across multiple PSPs
• Use data to increase authorization rates while reducing processing costs and losses
• Design and evaluate retry, failover, and fallback strategies to improve reliability and performance
• Analyze large-scale payment and risk data to identify product and platform improvements
• Build models and forecasts to understand the impact of policy and product changes
• Run experiments and measure tradeoffs between growth, risk, cost, and user experience
• Partner closely with Product, Engineering, Finance, and Operations to ship improvements to the payments platform
• Define metrics and dashboards to monitor performance and guide strategy
• Communicate clear, actionable recommendations to leadership and stakeholders

Key qualifications

• 10+ years of experience in payments, risk, credit, decision science, or platform analytics
• Strong hands-on skills in Python and SQL and working with large, messy datasets
• Experience working on high-scale transactional systems (payments, lending, marketplaces, fintech, or similar)
• Familiarity with concepts like authorization optimization, loss modeling, cohort/vintage analysis, or unit economics
• Strong product and business intuition—you care about shipping impact, not just analysis
• Comfortable operating cross-functionally and owning ambiguous, high-leverage problem spaces
• Background in fintech, payments, or large tech platforms is a strong plus

The national pay range for this role is $216,000-$270,000 base salary. Individual compensation will be commensurate with the candidate's experience aligned with Flex's internal leveling guidelines and benchmarks.

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, 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 stock options
• 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