Senior Software Engineer - AI Foundations

Toast creates technology to help restaurants and local businesses succeed in a digital world, helping business owners operate, increase sales, engage customers, and keep employees happy. Because our technology is purpose-built for restaurants, by restaurant people - and increasingly shaped by AI in both what we build and how we build - restaurants can trust that we'll deliver on their needs for today while investing in the experiences that will power their restaurant of the future. AI Foundations is Toast's internal platform team for AI. We build the infrastructure, governance, and developer tooling that makes AI a reliable, scalable force multiplier across the entire product development lifecycle. Our products include the LLM Proxy, AI Key Management, Observability pipelines, the Claude Plugin Marketplace, and autonomous agents that participate directly in the software development lifecycle. As a Senior Software Engineer on this team, you'll be hands-on building full-stack across the systems other Toast engineers depend on every day: the LLM proxy, agentic workflows, and the plugin marketplace that brings AI-native development practices to teams across the company. A day in the life (Responsibilities) Design, build, and ship features across AI platform infrastructure, including the LLM proxy, AI key management, and observability pipelines Develop and extend autonomous agents that participate in the SDLC, such as the AI Review GitHub App and Developer Platform MCP integrations Build on and contribute to the internal plugin marketplace, developing plugins that encode Toast's architectural standards and quality practices into AI assistant behavior Implement MCP (Model Context Protocol) services and service templates that make it faster and easier for teams across Toast to build AI-powered workflows Contribute full-stack across backend services and frontend or developer-facing interfaces as needed Write high-quality, well-tested code and participate in design and code reviews Partner closely with product management to shape feature requirements, contribute to roadmap discussions, and translate product vision into reliable technical solutions What you'll need to thrive (Requirements) 5+ years of experience designing and implementing scalable software systems, with a full-stack background spanning backend services and frontend or developer-facing interfaces Demonstrated experience building, deploying, or operating LLM-powered agents or AI-assisted developer tooling Familiarity with AI coding assistants (e.g., Claude Code, Cursor, GitHub Copilot) and an interest in extending them through custom plugins, skills, or hooks Experience with MCP (Model Context Protocol), tool use patterns, or agentic frameworks Working knowledge of prompt engineering and how LLM behavior responds to context and instructions Strong foundation in modern backend (Java, Kotlin, or similar) and frontend (TypeScript, React, or similar) technologies Experience with distributed systems, REST APIs, and cloud-native infrastructure Strong customer empathy and a drive to make developers' lives better through reliable, well-designed platform solutions What will make you stand out 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, internal tooling, or API gateways Familiarity with observability tooling for AI/LLM systems (e.g., Langfuse, DataDog) AI at Toast At Toast, one of our company values is that we're hungry to build and learn. We believe learning new AI tools empowers us to build for our customers faster, more independently, and with higher quality. We provide these tools across all disciplines, from Engineering and Product to Sales and Support, and are inspired by how our Toasters are already driving real value with them. The people who thrive here are those who embrace changes that let us buil