Member of Technical Staff (Software Engineering/Product)

AI Evaluation & Data Infrastructure | Frontier AI Systems

London, Full-time Onsite
£100k – £150k + meaningful equity (early stage)

We are working with an early-stage, stealth AI infrastructure company building the systems that sit behind how frontier AI models are evaluated, improved, and made reliable in production.

Rather than focusing on model development, the team is building the critical data and evaluation layer that enables AI systems to perform safely and effectively in high-stakes domains such as finance, healthcare, and legal.

This is a deeply technical, high-ownership engineering role at the intersection of software engineering, data infrastructure, and applied AI systems.

About the Role

As a Member of Technical Staff, you will design and build the core platform that powers AI evaluation and data generation workflows.

This includes developing annotation tooling, workflow systems, quality control pipelines, and LLM-integrated infrastructure that allows expert-driven insights to be turned into structured, model-ready datasets.

You will work across the full stack, from backend systems and data pipelines to product-facing interfaces and play a key role in shaping how the platform evolves.

Key Responsibilities

• Build and own end-to-end annotation and evaluation platforms.
• Design workflow systems for expert task creation, assignment, and review.
• Develop scalable data pipelines for structured AI training and evaluation datasets.
• Integrate LLM-powered tools for annotation assistance and automated validation.
• Collaborate with domain experts and founders to translate workflows into software systems.
• Make product and engineering decisions in ambiguous, fast-moving environments.
• Help define engineering standards and system architecture as the company scales.

About You

We are looking for engineers who thrive in high-agency environments and enjoy building from first principles.

You are likely a strong fit if you:

• Have experience building full-stack or platform-level systems in production.
• Are comfortable working across product, backend, and data infrastructure.
• Have experience or strong interest in LLMs and AI-assisted development tools.
• Enjoy solving ambiguous problems without detailed specifications.
• Take ownership from problem definition through to production delivery.
• Prefer building complete systems over isolated components.

Ideal Skills

• Experience building internal tools, workflow systems, or data platforms.
• Familiarity with React, TypeScript, Node.js, FastAPI, or similar stacks.
• Exposure to LLM evaluation, AI tooling, or reinforcement learning workflows.
• Background in early-stage startups or founding engineering roles.
• Interest in regulated or high-stakes domains (finance, healthcare, legal).