Applied AI Engineer Jobs in San Mateo, CA

About Sol

Sol is an agentic HR system built for how work is changing. We're replacing the traditional HRIS with an AI-native foundation. We are built for change, designed to scale, and reimagined with AI from the ground up, so HR leaders get a clear view of their workforce instead of a system everyone works around.

Sol was founded by leaders who spent decades building the modern HR category, and is backed by Sutter Hill Ventures and NEA. Our first customers go live in early 2027 and we need you to make them wildly successful.

The Role

You'll own the quality of Sol's AI capabilities: the systems that turn enterprise HR content and data into accurate, explainable answers and actions. This is applied work in the truest sense — the model is the easy part; making it reliable, auditable, and correct against real enterprise data is the job.

What You'll Do

• Design and build the AI systems that work over complex enterprise content and workforce data

• Build the evaluation infrastructure that tells us whether AI features actually work, before and after they ship

• Make build/buy/leverage decisions across the AI stack: embeddings, classifiers, foundation models, structured pipelines — and know when an LLM is the wrong tool

• Design for explainability and auditability from day one; our customers operate under regulations (EU AI Act, NYC Local Law 144) that make "the model said so" an unacceptable answer

• Work directly with the founding team to shape what the AI layer of an HR system should be

What We're Looking For

• You've built production AI systems from zero — not inherited platforms, not demos — and lived with the consequences of your infrastructure decisions

• You think pessimistically about failure modes: what happens when the model is wrong, when connected systems fail in creative ways

• You treat privacy, compliance, and explainability as core requirements, not obstacles

• You go deeper than managed platforms and notebooks — you understand what the infrastructure does underneath, because you've built equivalent capabilities yourself

• You use AI tools heavily in your own development workflow and have opinions about how to do it well

• You want to be a builder at an early-stage company: small team, broad ownership, fast iteration on a clean codebase

Why Now

The AI layer of this product is being designed right now, not retrofitted later. You'd join early enough that the architecture, the evaluation discipline, and the bar for what "correct" means are yours to set — and you'd be doing it in a category where getting AI right actually matters to people's livelihoods. Few applied AI roles offer this combination of blank canvas and real stakes.

Sol is an equal opportunity employer. We don't discriminate on the basis of race, color, religion, sex, national origin, age, disability, genetic information, sexual orientation, gender identity or expression, marital status, veteran status, or any other characteristic protected by applicable federal, state, or local law. We're committed to building an inclusive workplace and providing reasonable accommodations to qualified individuals with disabilities.