Principal Software Engineer, Core GenAI Platform

Upstart•San Mateo, CA

2d•Remote

About The Position

About Upstart Upstart is the leading AI lending marketplace partnering with banks and credit unions to expand access to affordable credit. By leveraging Upstart's AI marketplace, Upstart-powered banks and credit unions can have higher approval rates and lower loss rates across races, ages, and genders, while simultaneously delivering the exceptional digital-first lending experience their customers demand. More than 80% of borrowers are approved instantly, with zero documentation to upload. Upstart is a digital-first company, which means that most Upstarters live and work anywhere in the United States. However, we also have offices in San Mateo, California; Columbus, Ohio; Austin, Texas; and New York City, NY (opening Summer 2026). Most Upstarters join us because they connect with our mission of enabling access to effortless credit based on true risk. If you are energized by the impact you can make at Upstart, we’d love to hear from you! The Team Upstart’s GenAI Core Platform team builds the foundational infrastructure that democratizes access to generative AI across the company. As a Principal Software Engineer , you will provide technical leadership across multiple cross-functional teams, shaping the vision, architecture, and adoption strategy for our new GenAI platform for Engineers and non-Engineers alike. You will work closely with engineering leaders, ML researchers, and product stakeholders to ensure Upstart can scale the safe, efficient, and responsible use of LLMs across all business domains. This role goes beyond delivery. It is about setting long-term direction, de-risking our most ambitious AI initiatives, and raising the bar for technical excellence across the organization. In short, you will have a direct influence and impact on how we enable and implement GenAI and LLMs internally at Upstart.

Requirements

10+ years of professional software engineering experience, with at least 3 years leading large-scale, cross-team technical initiatives
Proven track record of delivering complex, distributed systems and platform infrastructure that span multiple teams
Deep expertise in backend systems and infrastructure technologies such as Kubernetes, Docker, Terraform, and cloud-native architectures
Experience designing and operationalizing ML/LLM platforms at scale, including optimization for cost, latency, and reliability
Demonstrated ability to set long-term technical direction and influence organizational strategy
Excellent communication skills with a history of driving alignment across engineering and business stakeholders

Nice To Haves

Full-stack engineering experience (Python, FastAPI, Kotlin, Spring, React/TypeScript, or similar)
Expertise in LLM-specific infrastructure such as inference optimization (quantization, ONNX, streaming), retrieval-augmented generation, and vector databases
Hands-on experience with LLM toolchains such as LangChain, LlamaIndex, or OpenAI APIs
Recognized as a technical leader beyond your immediate team, influencing platform strategy across organizations
Awareness of industry best practices and risks in GenAI including hallucination mitigation, fairness, explainability, and data privacy
Experience mentoring senior engineers and shaping organizational standards for operational excellence

Responsibilities

Define and drive the multi-year technical roadmap for the Core GenAI Platform, influencing adoption and alignment across several engineering teams
Lead architecture and design of large-scale, mission-critical systems for model inference, orchestration, and compliance
Identify and solve systemic technical risks that impact multiple teams and business-critical AI initiatives
Build high-leverage, generalizable platform components that meaningfully accelerate the productivity of engineers across Upstart
Mentor senior engineers (L5) and shape the growth of future technical leaders, fostering a culture of learning and excellence
Collaborate with VP-level and above leadership to influence business strategy with technical insight
Represent Upstart internally and externally as a thought leader in GenAI systems through executive reviews, cross-company forums, and industry venues
Establish operational standards for GenAI integrations, ensuring security, fairness, and reliability at scale