Senior Software Engineer, LLMs

Upstart

6h•Remote

About The Position

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. Upstart’s new Applied LLM team is building foundational infrastructure that democratizes access to generative AI for every product and engineering team across the company. This is a cross-functional team at the intersection of machine learning, product, and engineering. Our mission is to bring the power of ML - particularly large language models (LLMs) and generative AI - to life in Upstart’s core products. As a Senior Software Engineer focused on building LLM applications, you'll work closely with researchers, product managers, platform engineers, and designers to ship intelligent features that elevate the user experience and expand the capabilities of our systems.

Requirements

4+ years of software engineering experience, with 2+ years working directly on ML-driven products or intelligent systems
Proven ability to lead complex initiatives across engineering, product, and research stakeholders
Strong backend development skills (e.g., Python with FastAPI or Flask), plus experience with cloud-native tooling (e.g., Kubernetes, Docker, Terraform)
Experience integrating LLMs or ML models into production systems, including APIs and user-facing applications
Excellent communication skills and a collaborative, product-minded approach
Ability to think rigorously about system design, latency tradeoffs, and user impact when working with ML features

Nice To Haves

Experience shipping GenAI or LLM-powered features using frameworks like LangChain, LlamaIndex, or OpenAI APIs
Familiarity with retrieval-augmented generation (RAG), vector search (e.g., FAISS, Pinecone), and real-time inference patterns
Proficiency in full-stack development, including front-end work with React or similar frameworks
Strong intuition for prompt engineering, model testing, and evaluation methodologies
Experience navigating complex requirements around explainability, user trust, or compliance in ML applications
Track record of influencing architecture or product direction at a team or org level

Responsibilities

Design and build user-facing ML features that harness LLMs and generative AI to unlock new product capabilities
Partner with product, design, and ML research to prototype and deliver high-impact, ML-powered experiences
Own the technical architecture and implementation strategy for applied ML systems - balancing latency, observability, and iteration speed
Build scalable services and APIs that bring model outputs to users in trustworthy and intuitive ways
Collaborate across platform, infra, and legal/compliance teams to ensure ML deployments meet standards for safety, fairness, and performance
Establish and evangelize best practices for prompt design, model evaluation, and experimentation across the org

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!).