Senior AI Engineer: Experiential Data & RL Systems

Dex; Greater London; On-site; GBP 90,000 - 120,000; Full time

Job summary

Dex in London is seeking an experienced AI/ML researcher-engineer to own end-to-end problems in generating training data and integrating models with interactive software.

You will fine-tune models, build evaluation loops, and create observable systems, turning ambiguous questions into production outcomes. The role emphasizes hands-on development and robust tooling in collaboration with frontier AI labs.

Qualifications

• Directly fine-tuned or post-trained models with clear ownership and evaluation.
• Strong command of AI/ML fundamentals with practical SFT/RL/RLHF experience.
• Proficient in Python to build clean, testable production code.

Responsibilities

• Design and implement methods for generating and curating high-quality experiential data for AI agent training.
• Fine‑tune and post‑train large models using supervised fine‑tuning, reinforcement learning, and automated optimisation techniques.
• Build robust evaluation and feedback loops to measure and improve model and agent performance in interactive environments.
• Develop agent harnesses and sandboxed environments that connect AI models to complex software tasks.
• Take ambiguous research questions from initial concept through to production‑grade, observable AI systems.

Skills

Python

AI/ML fundamentals

SFT/RL/RLHF experience

Production-grade code

Job description

Dex in London is seeking an experienced AI/ML researcher-engineer to own end-to-end problems in generating training data and integrating models with interactive software.

You will fine-tune models, build evaluation loops, and create observable systems, turning ambiguous questions into production outcomes. The role emphasizes hands-on development and robust tooling in collaboration with frontier AI labs.