Principal Engineer, LLM (Platform and Tooling)

Upstart

9h•Remote

About The Position

At Upstart, the mission is to radically reduce the cost and complexity of borrowing for all Americans by leveraging creativity, experimentation, and advanced AI to reshape access to credit. As a leading AI lending marketplace, Upstart partners with banks and credit unions to expand access to affordable credit through technology that makes smarter, fairer decisions for millions of customers. The platform uses over one million predictions per borrower with more than 1,800 signals. Upstart operates as a digital-first company, offering most employees the flexibility to work remotely across 80+ cities in the US and Canada, while also fostering in-person connection through team onsites and planning sessions. Offices are located in Columbus, Austin, the Bay Area, and New York City (opening Summer 2026). The GenAI Core Platform team at Upstart is responsible for building the foundational platform that democratizes access to generative AI across the company. As a Principal Engineer - GenAI/LLM, this role involves providing technical leadership across multiple cross-functional teams, defining the vision, architecture, and adoption strategy for the new GenAI platform for both engineers and non-engineers. The Principal Engineer will collaborate with engineering leaders, ML researchers, and product stakeholders to ensure the scalable, safe, efficient, and responsible use of LLMs across all business domains. This position is crucial for setting long-term direction, de-risking ambitious AI initiatives, and elevating technical excellence within the organization, directly influencing the implementation and enablement of GenAI and LLMs internally at Upstart.

Requirements

Bachelor’s degree in Computer Science, Engineering, or Mathematics, or a related field (or its equivalent) + 8 years of experience
Deep expertise in LLM-specific infrastructure such as inference optimization (quantization, ONNX, streaming).
Ability to design scalable RAG architectures and manage the lifecycle of models from experimentation to high-availability production environments including vector databases.
Proven experience building robust, automated evaluation pipelines using both heuristic metrics and 'LLM-as-a-judge' frameworks to ensure model accuracy and safety.
Hands-on experience with LLM toolchains such as LangChain, LlamaIndex, or OpenAI APIs
Experience designing and operationalizing ML/LLM platforms at scale, including optimization for cost, latency, and reliability and the platform infrastructure needed to support them.
Deep Expertise in best practices and risks for GenAI including hallucination mitigation, fairness, explainability, and data privacy

Nice To Haves

12+ years of experience and 5+ leading cross functional technical initiatives
Proven ability to execute or guide model fine-tuning and alignment (RLHF/DPO) to optimize LLM performance for specialized consumer use cases and proprietary datasets.
Full-stack engineering experience (Python, FastAPI, Kotlin, Spring, React/TypeScript, or similar)
Deep expertise in backend systems and infrastructure technologies such as Kubernetes, Docker, Terraform, and cloud-native architectures

Responsibilities

Define and drive the multi-year technical roadmap for the Core GenAI Platform, influencing adoption and alignment across several engineering teams
Collaborate with CTO/VP-level and above leadership to influence business strategy with technical insight
Lead architecture and design of large-scale, mission-critical systems for model inference, orchestration, and compliance
Identify and solve systemic technical risks that impact the entire company and business-critical AI initiatives
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
Build high-leverage, generalizable platform components that meaningfully accelerate the productivity of engineers across Upstart
Mentor senior engineers, other principal engineers, and shape the growth of future technical leaders, fostering a culture of learning and excellence

Benefits

Competitive compensation, including base pay, bonus opportunities, and annual equity grants that vest quarterly
Generous 401(k) plan with Upstart matching $2 for every $1 contributed, up to $15,000 per year
Employee Stock Purchase Plan (ESPP) with discounted stock purchase options for eligible employees
Affordable medical, dental, and vision coverage, with multiple plan options - Upstart covers 90% to 100% of the cost depending on the plans you choose
Health Savings Account contributions from Upstart for eligible plans
Income protection benefits, including company-paid Basic Life, AD&D, and Short- and Long-Term Disability coverage, with options to purchase supplemental coverage
Paid time off, sick and safe time, and company holidays
Paid family and parental leave to support caregiving and major life moments
Family-centered benefits through Carrot and Cleo, supporting fertility, parenthood, and caregiving
Employee Assistance Program (EAP) offering mental health support and life-centered resources
Financial wellness resources, including access to financial planning tools and a financial concierge service
Annual wellness allowance to support your physical and emotional well-being and personal development, based on what matters most to you
Annual productivity allowance to invest in relevant tools and resources you need to do your best work, no matter where you work from
Connection and community through team events and onsites, all-company updates, and employee resource groups (ERGs)
Onsite perks, including catered lunches and fully stocked micro-kitchens when working from one of our four offices, located in the Bay Area, Austin, Columbus, and New York City (opening Summer 2026!).