Principal AI Engineer

Posted 3hrs ago

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Job Description

Principal AI Engineer defining LLM and agentic AI architecture for Rapid7’s cybersecurity platform. Building scalable models, inference systems, and evaluation standards for security products.

Responsibilities:

  • Define the architecture and technical roadmap for LLM and agentic AI systems across Detection and Response and Exposure and Remediation
  • Lead model strategy, including selection of frontier or open-source models and decisions about fine-tuning, distillation and post-training
  • Fine-tune, distill and post-train open-source LLMs on security data from curation through training, evaluation and deployment
  • Set engineering standards for context engineering, inference optimization and evaluation across teams
  • Optimize LLM inference at scale using speculative decoding, KV-cache management, continuous batching, quantization and custom kernels
  • Establish evaluations as the release gate for every AI system shipped
  • Lead design reviews and resolve complex technical trade-offs
  • Prototype and build critical model, training and inference code hands-on
  • Mentor Staff and Senior engineers
  • Shape product and platform investment
  • Build AI systems powering cybersecurity use cases including alert triage, threat investigation, automated response, vulnerability prioritization, attack surface risk assessment and guided remediation

Requirements:

  • 12+ years of software or ML engineering experience
  • 2+ years building production LLM or agentic AI systems
  • PhD in Computer Science, Machine Learning, AI or a related field preferred, or equivalent depth of expertise demonstrated through industry experience and technical contributions
  • Track record of building scalable, production-grade AI systems used across multiple teams or products
  • Deep understanding of transformer architecture, attention, tokenization, positional encodings, model training and serving
  • Ability to implement core LLM components from scratch
  • Expert-level PyTorch, including custom model code, training loops, mixed precision and distributed training such as FSDP and DeepSpeed
  • Hands-on full and parameter-efficient fine-tuning, including LoRA and QLoRA
  • Experience with distillation and preference or RL-based methods such as DPO and GRPO
  • Context engineering involving retrieval, memory and context management for long-running agent workflows
  • Deep knowledge of inference optimization, including prefill and decode, KV-cache management, continuous batching, speculative decoding, FlashAttention and quantization
  • Experience serving AI workloads at scale with vLLM, SGLang or TensorRT-LLM
  • Ability to define evaluation strategies and benchmarks for LLM and agent systems
  • Strong predictive AI and classical ML fundamentals
  • Strong distributed systems and Python fundamentals
  • Ownership of significant technical outcomes across multiple teams
  • Strong communication skills for explaining technical trade-offs
  • Ability to build cross-functional partnerships
  • Ability to connect customer needs and business priorities to technical decisions
  • Ability to embody the company’s core values
  • Preferred: experience pre-training or training LLMs from scratch
  • Preferred: experience writing GPU kernels using CUDA or Triton and profiling GPU workloads
  • Preferred: security domain experience such as detection engineering, SOC/MDR or vulnerability management
  • Preferred: experience running AI workloads on AWS at scale
  • Preferred: publications, patents or open-source AI contributions

Benefits:

  • Flexible/remote work arrangement indicated by the location options and #LI-Remote
  • Mentoring and technical leadership opportunities
  • Opportunity to shape product and platform investments
  • Collaborative, multi-dimensional team environment
  • Career development opportunity through challenging cybersecurity and AI work