Principal Software Engineer

About the role

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.

Your mission is to lead the architectural design, technical execution, and implementation of AI agents and infrastructure for Toast's Team area within our FinTech line of business. The Team area is a mission-critical space on which our restaurants rely to manage their staff and optimize their labor. As a Principal Engineer, you will serve as a key technical leader in the group, driving modern architectural patterns—including spec-driven development and agentic workflows—to deliver high-impact software.

A Day in the Life (Responsibilities)

- Define and execute the technical architecture for AI agents within the Team domain, ensuring systems are scalable, reliable, and secure.

- Partner closely with Engineering Managers and Product Managers to translate product roadmaps into robust technical designs and deliverables.

- Maintain a strong hands-on presence, writing code, prototyping new patterns, and resolving complex technical bottlenecks under load.

- Collaborate with Principal and Senior Principal Engineers across Toast to align on best practices, agent patterns, and spec-driven development paradigms.

- Guide, mentor, and elevate engineers within the Team area, fostering a culture of technical excellence and continuous learning.

What You'll Need to Thrive (Requirements)

- 10+ years of experience designing, building, and operating highly scalable, mission-critical distributed systems and SaaS products (ideally AWS-hosted).

- Proven track record of leading complex technical initiatives and delivering robust software architecture from design to production.

- Strong enthusiasm for agentic development practices, LLM integration, and modern software paradigms.

- Balanced expertise: Ability to design high-level technical solutions on a whiteboard while remaining deeply connected to code-level execution and system performance.

- Effective communication: Ability to articulate complex technical ideas clearly to both technical peers and product leadership.

What Will Help You Stand Out (Nice to Haves)

- Experience building systems that leverage LLMs, autonomous agents, or ML models.

- Hands-on experience with enterprise integration frameworks (e.g., Apache Camel) or event-driven messaging systems (e.g., Apache Pulsar).

- Experience establishing robust CI/CD, testing, and deployment strategies for complex systems.

- Domain knowledge in workforce management or restaurant operations.

Location: Remote (within Ireland) or Hybrid (Dublin)

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.