Principal Software Engineer, Cash Line

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 Cash Line is Upstart’s new always on revolving credit product designed to expand access to responsible, fairly priced credit. Instead of a traditional rewards driven credit card model, Cash Line rethinks how credit is structured and priced, using AI driven underwriting to better separate risk and reduce the need for cross subsidized rewards. We are a small, senior engineering team operating like a startup inside Upstart. The team owns the product end to end, from consumer facing experiences in the mobile app to the backend systems that power underwriting, pricing, servicing, and capital markets integrations. This is a high ownership environment. The codebase is new. The architecture is still being shaped. You will work closely with product, growth, finance, compliance, and capital markets partners to build a category defining credit experience. We are building with generative AI as a core capability from day one, both in the customer experience and in how we build and operate the product internally. How you’ll make an impact: Design and build the core backend systems that power a new revolving credit product used directly by consumers. Own distributed services that support underwriting, pricing, line management, transactions, and servicing with high reliability and observability. Translate complex product and economic requirements into scalable technical systems, balancing speed, risk, and long term maintainability. Partner closely with machine learning engineers and data teams to productionize models and integrate AI driven decisioning into real time user flows. Collaborate with mobile engineers to deliver seamless consumer facing features, ensuring backend systems are optimized for real world usage patterns. Work across the full lifecycle of credit, from consumer acquisition and onboarding through funding, servicing, and capital markets distribution. Shape foundational architectural decisions in a greenfield environment, while thoughtfully integrating with systems from Upstart’s mature lending platform. Contribute to a Gen AI first product strategy, helping define how generative AI enhances user experience, internal tooling, automation, and operational workflows. Raise the bar for engineering quality through strong API design, data modeling, observability, testing, and operational rigor. Minimum Qualifications Bachelor’s degree in Computer Science, Engineering, or Mat