Senior Software Engineer (AI)

A high-growth startup is building the infrastructure to measure how LLMs actually perceive and process data, giving teams visibility into model behavior that's historically been a black box. They're hiring a Senior Software Engineer to join the founding team for a true 0→1 opportunity, architecting the core product alongside a small, technical founding group.

You'll move fluidly across frontend, backend, and applied AI, including building and orchestrating AI agents end to end, with real ownership in a fast-paced, autonomous environment.

The Stack

TypeScript/React on the frontend, Python on the backend. You'll be working directly with LLMs and model outputs, building the evaluation and measurement frameworks from scratch.

What You'll Do

• Own full stack architecture decisions from day one, spanning frontend to backend
• Design and build systems that evaluate and quantify LLM perception of structured and unstructured data
• Build and orchestrate agentic workflows for automated evaluation, data processing, and model behavior analysis
• Work directly with LLMs and model outputs to build novel measurement and evaluation frameworks
• Ship product end to end, from data pipelines to user-facing interfaces
• Set technical standards and engineering culture as one of the first hires
• Work directly with founders and have real say in product features, roadmap, and technical decisions

What Makes You a Fit

• Strong full stack experience with TypeScript, React, and Python in production environments
• Hands-on experience building with or around LLMs, whether that's evals, fine-tuning, RAG, or applied AI product work
• Founding engineer, founder, or very early-stage startup experience, comfortable with ambiguity and moving/shipping fast
• Genuinely excited to be hands-on at every layer of the stack

Why This Role

One of the first engineering hires at a high-growth, well-backed startup tackling a problem that's only getting more critical as LLMs get embedded everywhere. Huge ownership, huge technical surface area, and a real seat at the table for foundational product decisions.