Principal Engineer, AI Systems

Responsibilities

• Ship, architect, and own end-to-end delivery of autonomous agents and agentic workflows
• Design agent orchestration systems including planning, tool use, memory, and multi-agent coordination
• Integrate and optimize frontier LLMs into agent architectures
• Drive model optimization work including fine-tuning, distillation, and RLHF
• Lead technical planning and provide mentorship to engineers across experience levels
• Partner with stakeholders to translate business objectives into agent-powered product experiences

Requirements

• 15+ years of experience in software engineering or machine learning
• Professional experience building autonomous agents or agentic workflows in production
• Fluency in context management, planning, tool use, memory, and multi-step reasoning
• Hands-on experience with prompt engineering, RAG, and model optimization
• Proven track record of scaling AI-powered products in fast-paced environments
• Strong software engineering fundamentals and architectural decision-making skills
• Ability to navigate extreme ambiguity in an evolving domain

Preferred Qualifications

• Experience at leading AI organizations translating research into production systems
• Background building or scaling agentic products at startups
• Experience with model fine-tuning, distillation, or RLHF
• Familiarity with agent evaluation, safety, and alignment challenges

About the Company

Block builds simple, powerful tools that make progress towards an economy that's truly open to all. Our brands include Square, Cash App, Afterpay, TIDAL, Bitkey, and Proto.