Sr. Lead AI Engineer

ABOUT THE ROLE As a Senior Lead AI Engineer at Klaviyo, you will be a key player in shaping the future of software by developing systems that can run, optimize, and adapt themselves based on outcome and reward signals. Our company has already built a robust infrastructure and applications that connect businesses and consumers, serving 183,000+ customers, billions of consumer profiles, and hundreds of billions of messages and conversion events. We're now investing heavily in Marketing AI and Service AI, the shared services and agentic capabilities that power AI-native experiences across Klaviyo. As a technical leader in the AI & Analytics organization, you will own the architecture and execution for complex, distributed backend systems, guide other engineers through design and implementation, and partner closely with product, machine learning, and data science teams to turn AI ideas into reliable, scalable production capabilities. This is a hands-on tech lead role, not a people-manager role. WHAT YOU'LL DO Your primary responsibilities will include: - Defining and improving the engineering architecture for Service and Marketing AI capabilities, leading the design of scalable, low-latency backend systems and APIs that power our AI products and agents for 183K+ customers. - Building and hardening AI serving systems, including services that host and orchestrate AI models (LLMs, tools, evaluators, retrieval systems), with clear contracts, SLOs, and observability. - Evolving our agentic architecture, driving the technical roadmap for Service and Marketing AI agents to improve tool use, autonomy, and reliability. - Setting engineering standards for AI services, establishing best practices for evaluation, safety/guardrails, prompt and model versioning, offline and online tests, and incident response for AI-backed systems. - Leading cross-team technical work, acting as the primary technical interface between Service / Marketing AI and other product/platform teams. - Mentoring and upleveling engineers, coaching senior and mid-level engineers through design, implementation, and operational best practices. - Helping build the Palo Alto hub, shaping local engineering rituals, and creating healthy patterns for cross-hub collaboration. - Measuring what matters, defining and tracking key metrics for your systems, and using those insights to drive roadmap and technical decisions. WHAT YOU'LL NEED To be successful in this role, you will need: - 8+ years of professional software engineering experience with a strong focus on backend and distributed systems, having led complex projects or areas end-to-end and acted as the go-to technical owner for key services. - Hands-on experience with generative and agentic AI in production, having built and shipped generative or agentic AI applications. - Deep experience with large-scale distributed systems, having architected and operated reliable services, async processing pipelines, and distributed task queues. - Strong Python and data tooling fluency, being proficient in Python and modern backend frameworks, with experience using big data tools and ORMs. - Production-grade cloud experience, being comfortable with AWS and Kubernetes, CI/CD pipelines, observability, and operational best practices. WHY REMOTE As a remote employee, you will have the flexibility to work from anywhere, while still being part of a collaborative and dynamic team. You will be able to contribute to the