Founding AI Engineer — Security, Equity & Visa (London)

Refractal; Greater London; On-site; GBP 90,000 - 150,000; Full time

Benefits offered by this job

Founding equity

Competitive salary

Visa sponsorship

In‑person London office

Job summary

Refractal is building security infrastructure for autonomy in London and is at the very earliest startup stage. You will join as one of the first engineering hires after the technical co‑founder, owning parts of the platform from day one and growing toward Head of Engineering.

You will work on runtime classification, policy enforcement, evidence pipelines, and a policy engine, with autonomy, direct customer impact, and a clear path to leading the engineering org as we scale.

Qualifications

• 0–3 years of post‑university experience in AI/ML systems.
• Strong foundation in computer science, machine learning, cybersecurity, or a related field.
• Evidence of exceptional building ability through production systems, research at a leading lab, startup experience, or open‑source contributions.
• Rigorous understanding of how AI systems fail and how adversaries can exploit them.
• The ability to work independently, move quickly, and take ownership of complex technical problems.
• Strong communication skills and an interest in growing into a technical leadership role.

Responsibilities

• Developing the runtime classification stack that decides whether an agent's proposed action is authorised before it executes.
• Designing policy enforcement at the action boundary: allowing, blocking, or letting flagged actions proceed with sensitive data redacted.
• Building evidence pipelines that record every AI action, verdict, and rationale.
• Developing the policy engine that compiles natural‑language policies and regulation into executable runtime controls.
• Building multimodal ingestion and detection.
• Collaborating with our security research function to turn novel attacks into shipped detections and controls.
• Owning systems end to end and shipping to production with real, high‑consequence customer deployments.

Skills

AI/ML Systems

Security

Systems Design

Production ML

Open Source

Education

CS/ML/Cybersecurity degree

Job description

Refractal is building security infrastructure for autonomy in London and is at the very earliest startup stage. You will join as one of the first engineering hires after the technical co‑founder, owning parts of the platform from day one and growing toward Head of Engineering.

You will work on runtime classification, policy enforcement, evidence pipelines, and a policy engine, with autonomy, direct customer impact, and a clear path to leading the engineering org as we scale.