Principal Software Engineer, Unsecured Installments

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 Unsecured Installments is one of Upstart’s core lending products, helping borrowers access credit through a seamless, digitally native experience. The team owns critical parts of the borrower journey across offer generation, pricing, underwriting, funding, and borrower experience, while working closely with the broader lending platform that powers Upstart at scale. We operate in a high-ownership environment where engineering plays a direct role in shaping product strategy, credit outcomes, and platform evolution. This team works on complex, high-leverage problems at the intersection of software, machine learning, economics, and compliance. Recent work has focused on improving borrower flows, repricing and rate flexibility, partnership experiences, and the technical health of the platform. As a Principal Software Engineer, you’ll help define the technical direction for a broad and business-critical surface area. You’ll partner closely with product, machine learning, analytics, compliance, and other engineering teams to build systems that are reliable, scalable, and adaptable as the product continues to evolve. How you’ll make an impact: Design and evolve the core backend systems that power Upstart’s unsecured installment lending product. Lead architecture and technical direction across complex domains such as underwriting, pricing, offer generation, funding, servicing, and borrower lifecycle workflows. Translate product, economic, and operational requirements into scalable technical systems that balance speed, reliability, and long-term maintainability. Partner closely with machine learning engineers and data teams to productionize models and integrate decisioning systems into real-time borrower experiences. Improve the systems and services behind key borrower and partner flows, including experimentation, repricing, and moments of borrower friction. Influence architectural decisions across team boundaries, helping connect the Unsecured Installments roadmap with Upstart’s broader lending platform and shared infrastructure. Raise the bar for engineering quality through strong API design, thoughtful domain modeling, observability, testing, and operational excellence. Mentor other engineers and serve as a technical leader who can bring clarity, drive alignment, and help teams execute through ambiguity. Contribute to how the team uses AI in development workflows and product capabilities, with a pragmatic view of where it can create meaningful leverage. Minimum Qualifications  Bachelor’s degree in Computer Science, Engineering, Mathematics, or a related field (or equivalent practical experience) and 8+ years of software engineering experience. Strong experience designing distributed systems and event-driven architectures, including real-world handling of retries, idempotency, fault tolerance, and failure modes. Proficiency in an object-oriented language such as Python, Java, Kotlin, C#, or Ruby, with deep experience building APIs and service-oriented backend systems. Track record of leading technical design and delivery for large-scope, business-critical systems. Ability to work effectively in ambiguous environments where product requirements, operating constraints, and system boundaries evolve over time. Strong cross-functional collaboration skills and comfort working closely with product, analytics, compliance, risk, and other business stakeholders. Experience influencing technical direction beyond a single team, including driving alignment across engineers with different priorities and constraints. Active use of AI tools in engineering workflows, with a thoughtful perspective on how AI is reshaping software development. Exceptional communication and collaboration skills, with the ability to explain complex tradeoffs and advocate for high-impact solutions. Preferred Qualifications Experience in fintech, lending, payments, or other regulated financial systems. Familiarity with unsecured installment lending, offer and pricing systems, borrower acquisition flows, funding, or servicing platforms. Experience building systems that support experimentation, repricing, or other dynamic product and decisioning workflows. Background working with machine learning-driven underwriting, pricing, or risk systems. Experience operating as a technical leader on small or midsized teams