Principal Software Engineer, Cash Line

Upstart is a leading AI lending marketplace focused on reducing the cost of borrowing for Americans. The Principal Software Engineer will design and build backend systems for a new revolving credit product, working closely with cross-functional teams to integrate AI-driven decisioning and enhance user experience.

Responsibilities:

• 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

Requirements:

• Bachelor's degree in Computer Science, Engineering, or Mathematics, or a related field (or its equivalent) + 8 years of 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, and experience building and maintaining APIs and service oriented architectures
• Experience shipping consumer facing features end to end, with a strong understanding of latency, reliability, and user impact
• Ability to work effectively in ambiguous, zero to one environments where requirements evolve quickly
• Strong cross functional collaboration skills and comfort working closely with product, finance, compliance, and other business stakeholders
• Active use of AI tools in engineering, with a forward-looking perspective on how AI is reshaping software development
• Exceptional communication and collaboration skills; able to align teams and advocate for high-impact solutions across functions
• Experience in fintech, credit, payments, or other regulated financial systems
• Familiarity with revolving credit, line management, transaction processing, or ledger based systems
• Experience building systems that sit at the intersection of consumer products and capital markets infrastructure
• Background working with ML driven pricing, underwriting, or risk systems
• Hands on experience leveraging generative AI in product features or internal engineering workflows
• Experience on small, high ownership teams where engineers are responsible for architecture, implementation, and operational excellence
• Passion for building products that expand access to credit and improve financial outcomes for underserved consumers