Principal Software Engineer - AI Foundations at Toast

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 Principal Software Engineer, you'll set the technical direction for how we design, build, and evolve these systems, working full-stack across the agentic workflows that employees across Toast depend on every day. This role is for someone who can drive architecture, raise the engineering bar across the team, and stay hands-on building. A day in the life (Responsibilities) • 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 What you'll need to thrive (Requirements) • 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 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 or internal tooling • Familiarity with observability tooling for AI/LLM systems (e.g., Langfuse, DataDog) **This role requires a minimum of two days per week in our Dublin office** 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 build more for our customers; it’s a core part of our culture. Our Total Rewards Philosophy We strive to provide competitive compensation and benefits programs that help to attract, retain, and motivate the best and brightest people in our industry. Our total rewards package goes beyond great earnings potential and provides the means to a healthy lifestyle with the flexibility to meet Toasters’ changing needs. Learn more about our benefits at [Upgrade to PRO to see link] How Toast Uses AI in its Hiring Process Throughout the hiring process, our goal is to get to know you. We use AI tools to support our recruiters and interviewers with tasks like note-taking, summarization, and documentation of interviews to ensure they can be fully focused on your conversation. All hiring decisions are made by people. To learn more: [Upgrade to PRO to see link] Diversity, Equity, and Inclusion is Baked into our Recipe for Success At Toast, our employees are our secret ingredient—when they thrive, we thrive. The restaurant industry is one of the most diverse, and we embrace that diversity with authenticity, inclusivity, respect, and humility. By embedding these principles into our culture and design, we create equitable opportunities for all and raise the bar in delivering exceptional experiences. We Thrive Together We embrace a hybrid work model that fosters in-person collaboration while valuing individual needs. Our goal is to build a strong culture of connection as we work together to empower the restaurant community. To learn more about how we work globally and regionally, check out: [Upgrade to PRO to see link] Apply today! Toast is committed to creating an accessible and inclusive hiring process. As part of this commitment, we strive to provide reasonable accommodations for persons with disabilities to enable them to access the hiring process. If you need an accommodation to access the job application or interview process, please contact [Upgrade to PRO to see contact]. ------ For roles in the United States, it is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability.