We are looking for a Principal Software Engineer to join our Agentic Engineering team. You will architect guardrail systems spanning multiple services and domains, establish standards for validation, enforcement, and observability, and anticipate misuse and system failure modes before they manifest. You will also set architectural direction for backend services, APIs, and integrations that apply software engineering discipline to govern how AI-driven systems behave across the engineering workflow. This is a senior technical leadership role requiring deep proficiency in Python and TypeScript, a track record of designing systems that operate reliably at organizational scale, and the ability to set standards that shape how enforcement is practiced across teams. What You'll Do • Architect guardrail and enforcement systems spanning multiple services, domains, and team boundaries • Establish standards for validation, enforcement, observability, and safe execution across the platform • Anticipate misuse and system failure modes and design preventive controls before incidents occur • Set direction for shared backend services, APIs, and platform components at organizational scale • Define reusable abstractions, enforcement patterns, and integration standards adopted organization-wide • Influence engineering culture around defensive design, constraint modeling, and systems reliability What Differentiates This Role This role is focused on how systems behave under misuse, failure, or unexpected inputs - not on building user-facing features. At this level, you are setting the standards that define how enforcement works across the organization. You anticipate problems that haven't happened yet, design the systems that prevent them, and establish the patterns that make safe behavior the default rather than the exception. What You Will Bring • 8-12+ years of software engineering experience with deep proficiency in Python and TypeScript • Demonstrated experience architecting production systems that span multiple services and teams • Track record of defining enforcement, validation, or safety standards adopted across an organization • Experience designing systems that anticipate adversarial inputs, non-deterministic behavior, and edge case failures • Ability to set architectural direction and establish reusable patterns for cross-team adoption • Experience mentoring senior and lead engineers on system design, constraint modeling, and defensive architecture • Strong written and verbal communication - able to present system-level strategy to engineering leadership • Working experience with Terraform for AWS infrastructure at organizational scale • Experience with agentic or multi-step workflow systems involving autonomous tool orchestration Nice to Have • Experience designing LLM safety or guardrail systems end-to-end (not just integration) • Track record of influencing engineering culture or establishing organization-wide technical standards • Experience with agentic or multi-step workflow systems involving autonomous tool orchestration • Open-source contributions to public GitHub projects • Background in platform engineering, developer tooling, or infrastructure standards at enterprise scale Work Environment Hybrid work. Candidates must be located in the Farmington Hills / Metro Detroit, Michigan area. No remote candidates. Principal Software Engineer, Agentic Engineering At Fifth Third, we understand the importance of recognizing our employees for the role they play in improving the lives of our customers, communities and each other. Our Total Rewards include comprehensive benefits and differentiated compensation offerings to give each employee the opportunity to be their best every day. The base salary for this position is reflective of the range of salary levels for all roles within this pay grade across the U.S. Individual salaries within this range will vary based on factors such as role, relevant skillset, relevant experience, education and geographic location. In addition to the base salary, this role is eligible to participate in an incentive compensation plan, with any such payment based upon company, line of business and/or individual performance. Our extensive benefits programs are designed to support the individual needs of our employees and their families, encompassing physical, financial, emotional and social well-being. You can learn more about those programs on our 53.com Careers page at: https://www.53.com/content/fifth-third/en/careers/benefits.html or by consulting with your talent acquisition partner. LOCATION -- Farmington Hills, Michigan 48334 Attention search firms and staffing agencies: do not submit unsolicited resumes for this posting. Fifth Third does not accept resumes from any agency that does not have an active agreement with Fifth Third. Any unsolicited resumes - no matter how they are submitted - will be considered the property of Fifth Third and Fifth Third will not be responsible for any associated fee.