Senior Software Engineer, LLM Platform

The Team

Upstart’s new LLM Platform team is building foundational infrastructure that democratizes access to generative AI for every product and engineering team across the company.

As a Senior Software Engineer on the LLM  Platform team, you will help design and build a unified interface for securely interacting with large language models - abstracting away the complexity of model selection, prompt orchestration, evaluation, and scaling. You'll help build a centralized GenAI layer that enables engineers to use best-in-class LLMs through clean APIs, configurable pipelines, and intuitive tooling.

Reporting to our Senior Director of Engineering, the team operates with broad scope and high visibility, partnering across Machine Learning, Product, and Compliance to ensure every model integration is performant, secure, and compliant. Whether it's embedding LLMs in user-facing products or optimizing backend workflows, this team makes it seamless for Upstart Engineering to adopt and scale GenAI company-wide.

How you’ll make an impact:

• Build the LLM Platform powering generative AI use cases across all of Upstart Engineering.
• Design and implement reliable, observable infrastructure for model inference, prompt orchestration, and data workflows.
• Drive cross-functional adoption of AI tooling by delivering reusable components and intuitive interfaces.Increase developer productivity through automation, metrics dashboards, and streamlined GenAI integrations.
• Set the technical roadmap for platform capabilities, balancing innovation with reliability and compliance.
• Partner with ML researchers, product engineers, and design to bridge experimentation and production.
• Ensure the platform adheres to emerging standards of security, fairness, and explainability for LLM systems.

What we’re looking for: 

• Minimum requirements:
  • 6+ years of experience in object-oriented software engineering, with a strong systems engineering background
  • Proficiency in backend development, microservices architecture, and infrastructure tools like Kubernetes, Docker, and Terraform
  • Hands-on experience building ML platforms or infrastructure supporting LLMs or inference systems
  • Familiarity with observability tools (e.g., Prometheus, Grafana, Datadog) and data processing pipelines
  • Strong written and verbal communication skills and a collaborative approach to cross-functional work
• Preferred qualifications:
  • Full Stack development skills, ideally with Kotlin, Spring, JS/TS (React) or similar
  • Experience with LLM toolchains such as LangChain, LlamaIndex, or OpenAI APIs
  • Deep understanding of model inference optimization (e.g., quantization, ONNX, streaming)
  • Exposure to retrieval-augmented generation (RAG), vector databases (e.g., FAISS, Pinecone), or prompt engineering
  • Experience operationalizing LLMs in production, including latency management and prompt versioning
  • Ability to influence platform direction and drive alignment across multiple engineering teams
  • Awareness of LLM-specific risk domains, including hallucinations, fairness, and data privacy

Position Location - This role is available in the following locations: Remote, San Mateo, Columbus, Austin 

Time Zone Requirements - This team operates across all U.S. time zones.

Travel Requirements - This team has regular on-site collaboration sessions. These occur 3 days per quarter at an Upstart office. If you need to travel to make these meetups, Upstart will cover all travel related expenses.

What you'll love: 

• Competitive Compensation (base + bonus & equity)
• Comprehensive medical, dental, and vision coverage with Health Savings Account contributions from Upstart 
• 401(k) with 100% company match up to $4,500 and immediate vesting and after-tax savings
• Employee Stock Purchase Plan (ESPP)
• Life and disability insurance
• Generous holiday, vacation, sick and safety leave  
• Supportive parental, family care, and military leave programs
• Annual wellness, technology & ergonomic reimbursement programs
• Social activities including team events and onsites, all-company updates, employee resource groups (ERGs), and other interest groups such as book clubs, fitness, investing, and volunteering
• Catered lunches + snacks & drinks when working in offices

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