Principal Software Engineer - AI Foundations

Toast builds technology for restaurants. AI Foundations is the internal AI platform team. This Principal Software Engineer will define architecture, work full-stack, and deliver autonomous agents and MCP services.

• Define and drive the technical architecture for AI Foundations platform, spanning backend services, frontend tooling, and third party integrations
• Lead full-stack design and delivery across the LLM proxy, AI key management, observability pipelines, and internal plugin marketplace
• Architect and deliver autonomous agents and MCP services that participate in the software development lifecycle
• Set and uphold engineering standards across the team: code quality, system design, testing, and operational practices
• Mentor and technically lead engineers across all levels through design reviews, code reviews, and pairing
• Partner with product and platform leadership to shape the AI Foundations roadmap and translate strategy into executable technical plans
• Collaborate closely with designers and product teams to translate UX concepts into polished, production-ready frontend experiences
• Serve as a key technical voice in cross-team discussions, representing AI Foundations in architecture decisions across Toast engineering

• 10+ years of experience designing and delivering scalable software systems, with a strong full-stack background spanning backend services and frontend or developer-facing interfaces
• Demonstrated experience leading technical architecture for a platform, product, or engineering team
• Proven ability to mentor engineers and raise the technical bar of a team through standards, reviews, and hands-on guidance
• Experience building, deploying, or operating LLM-powered agents or AI platform infrastructure
• Familiarity with AI coding assistants (e.g., Claude Code, Cursor, GitHub Copilot) and experience extending them through custom plugins, skills, or hooks
• Experience with MCP, tool use patterns, or agentic frameworks
• Strong foundation in modern backend (Java, Kotlin, or similar) and frontend (TypeScript, React, or similar) technologies, with demonstrated experience building user-facing product interfaces
• Comfort with a rapidly changing technical landscape and a bias towards action over analysis paralysis
• Familiarity with A2A (Agent-to-Agent) protocols and multi-agent orchestration patterns
• Experience with machine learning concepts, model evaluation, or ML infrastructure
• Experience building developer experience platforms or internal tooling
• Familiarity with observability tooling for AI/LLM systems (e.g., Langfuse, DataDog)