Principal Applied Scientist

About Upstart At Upstart, we’re united by a mission that matters: to radically reduce the cost and complexity of borrowing for all Americans. Every day, we bring creativity, experimentation, and advanced AI to reshape access to credit, helping millions move forward financially with clarity and confidence. As the leading AI lending marketplace, we partner with banks and credit unions to expand access to affordable credit through technology that’s both radically intelligent and deeply human. Our platform runs over one million predictions per borrower using more than 1,800 signals, powering smarter, fairer decisions for millions of customers. But the numbers only hint at the impact. Every idea, every voice, and every contribution moves us closer to a world where credit never stands between people and their financial progress. We’re proudly digital-first, giving most Upstarters the flexibility to do their best work from wherever they thrive, alongside teammates across 80+ cities in the US and Canada. Digital-first doesn’t mean distant. We’re intentional about in-person connection through team onsites, planning sessions, and moments that spark creativity and trust. And whether you choose to work primarily from home or collaborate in-person from one of our offices in Columbus, Austin, the Bay Area, or New York City (opening Summer 2026), you’ll have the support to work in the way that works best for you. If you’re energized by tackling meaningful problems, excited to innovate with purpose, and motivated by work that truly matters, we’d love to hear from you. The Team: Upstart’s Growth and Marketplace Optimization teams are responsible for building the decision systems that determine how offers are presented, optimized, and evolved across the customer journey. These systems sit at the intersection of machine learning, optimization, pricing, marketplace dynamics, and borrower behavior. The work spans partner channels, onsite experiences, and marketplace optimization, with the goal of improving conversion, borrower experience, lender surplus, and overall marketplace efficiency. As these systems continue to evolve, the organization is investing in a more unified technical vision that connects decision-making across stages rather than optimizing individual components in isolation. The Role: As a Principal Applied Scientist at Upstart, you will help define the long-term technical direction for some of Upstart’s most important offer optimization and conversion modeling systems. You will work across multiple teams to define how conversion modeling, offer optimization, and system design should fit together, ensuring models and optimization systems account for downstream effects, marketplace constraints, and customer outcomes. This role is intentionally broad and high leverage. You will help structure ambiguous problem spaces, design solutions that account for interactions across multiple stages of the customer journey, and provide technical oversight to ensure work across multiple teams converges toward a coherent long-term vision. The work sits at the intersection of operations research, optimization, causal machine learning, and production decision systems. How you’ll make an impact: Define the technical vision for how offer decisioning systems should interconnect across partnerships, always-on systems, and marketplace optimization Build and guide conversion modeling approaches that optimize decisions across multiple stages of the customer journey rather than in isolated local steps Ensure models and decision policies at one stage account for downstream impacts, business constraints, and later-stage optimization opportunities Design interfaces between decision systems and optimization or constraint-specification components Drive cross-functional technical alignment across teams that currently own adjacent pieces of the problem Scope and lead large, ambiguous initiatives that require both deep modeling judgment and strong systems thinking P