Staff AI Systems Engineer — Frontier Models

Dex; Greater London; On-site; GBP 120,000 - 180,000; Full time

Job summary

Dex is partnering with frontier AI teams to build advanced autonomous agents and production-grade AI systems. You will join as a Member of Technical Staff responsible for end-to-end research engineering across model post-training, evaluation loops, and sandbox execution environments.

You will implement hands-on training, fine-tuning, and deployment pipelines, turning open-ended questions into scalable architectures and production-ready software with engineers.

Qualifications

• Direct, hands-on experience training, fine-tuning, or post-training models with SFT/RL/RLHF.
• Strong Python software engineering fundamentals and production-quality code.
• Ability to lead technical initiatives across multi-month horizons.

Responsibilities

• Fine-tune and post-train models using SFT, RL, or RLHF.
• Build and scale data creation and curation pipelines for synthetic training data.
• Design evaluation harnesses and benchmarks for agent performance.
• Develop resilient agent harnesses and sandboxed environments for real apps.
• Prototype new training and agent workflows and productionise winning approaches.

Skills

SFT

RL

RLHF

Python

Production-grade systems

Multi-month initiatives

Tools

Git

Docker

Linux

Job description

Dex is partnering with frontier AI teams to build advanced autonomous agents and production-grade AI systems. You will join as a Member of Technical Staff responsible for end-to-end research engineering across model post-training, evaluation loops, and sandbox execution environments.

You will implement hands-on training, fine-tuning, and deployment pipelines, turning open-ended questions into scalable architectures and production-ready software with engineers.