Senior Machine Learning Engineer

Senior ML Engineer (LLM & Reinforcement Learning)Boston - Hybrid/Remote$150,000 -$230,000 + Equity + PTOAre you a Senior ML Engineer with experience building production-grade LLM systems looking to take ownership of autonomous, multi-agent architectures within a high-growth cybersecurity AI start-up?This is an opportunity to join a fast-growing AI company developing next-generation autonomous offensive security platforms. You will join a specialized AI engineering team and play a critical role in advancing their flagship platform, moving the needle on complex problems like exploit chaining, multimodal vision, and co-evolutionary self-training loops.In this role, you will design, implement, and optimize highly sophisticated multi-agent architecture, while contributing directly to model fine-tuning and production scalability. Working closely with engineering leadership and cross-functional teams, you will transition advanced multi-agent systems from cutting-edge experimentation into robust, production-ready enterprise solutions.This role would suit an ML Engineer who enjoys solving deep, technical agent-orchestration challenges and wants to be a foundational builder of autonomous, self-improving security systems.The Role: *Design and improve multi-agent architectures, planning loops, and tool-use*Contribute to model training via data curation, Supervised Fine-Tuning, and preference optimization (DPO/GRPO)*Build evaluation harnesses to track model and agent performance*Optimize inference for latency and throughput using vLLM or TensorRT-LLM*Deploy and scale production agents within Kubernetes environmentsThe Person: *Experience building production ML systems, with a strong focus on LLMs or LLM-powered agents*Strong Python programming alongside PyTorch and Hugging Face*Experience with Supervised Fine-Tuning, preference optimization, and synthetic data generation*Experience shipping multi-agent or tool-using LLM systems to production*US Citizen