Principal AI Engineer — Scalable Security AI Systems

Divvy Cloud Corp.; Belfast City District; Hybrid; GBP 120,000 - 150,000; Full time

Job summary

Rapid7 is seeking a Principal AI Engineer to set the technical direction for LLM and agentic AI systems across its security products. You will stay hands-on with the hardest problems, guiding model strategy and implementation from data curation through training and deployment.

You will mentor Senior engineers, define engineering standards, and lead design reviews to balance quality, latency, and cost. Experience with security-domain AI and scalable deployments is highly valued.

Qualifications

• 12+ years of software or ML engineering experience, including 2+ years building production LLM or agentic AI systems.
• A PhD in Computer Science, Machine Learning, AI or a related field is preferred, or equivalent depth of expertise demonstrated through industry experience and technical contributions.
• Track record of building scalable, production-grade AI systems with cross-team impact and technical leadership.

Responsibilities

• Define the architecture and technical roadmap for LLM and agentic AI systems across Detection and Response and Exposure and Remediation.
• Lead model strategy: frontier vs open-source models; fine-tune, distill, or post-train as appropriate.
• Fine-tune, distill and post-train open-source LLMs on security data, from data curation through training, evaluation and deployment.
• Set engineering standards for context engineering, inference optimization, and evaluation across teams.
• Optimize LLM inference at scale with techniques like speculative decoding, KV-cache management, continuous batching, quantization and custom kernels.
• Establish evals as the release gate for every AI system shipped.
• Lead design reviews and resolve the hardest technical trade-offs.
• Stay hands-on: prototype and build critical model, training and inference code.
• Mentor Staff and Senior engineers and shape product and platform investments.

Skills

LLMs from first principles

PyTorch expert

Fine-tuning & post-training

Context engineering

Inference optimization

Evals & benchmarking

Distributed systems

Leadership & mentoring

Cross-functional collaboration

Strong communication

Product/leadership influence

Education

PhD in CS/ML preferred

Job description

Rapid7 is seeking a Principal AI Engineer to set the technical direction for LLM and agentic AI systems across its security products. You will stay hands-on with the hardest problems, guiding model strategy and implementation from data curation through training and deployment.

You will mentor Senior engineers, define engineering standards, and lead design reviews to balance quality, latency, and cost. Experience with security-domain AI and scalable deployments is highly valued.