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Klaviyo is seeking a Senior Full Stack Engineer to help build Customer Agent, an AI-native conversational platform. You'll work across the full stack to design, build, and scale systems powering intelligent workflows, conversational experiences, tool integrations, retrieval systems, onboarding flows, observability, and multi-channel customer engagement.
The Customer Agent team is building one of Klaviyo's most strategic product areas: an extensible AI platform enabling brands to deliver personalized, autonomous customer experiences across chat, email, SMS, and beyond. The team operates with high ownership, rapid iteration cycles, and a strong bias toward execution.
In this role, you'll tackle complex technical and product challenges, develop multiple solution paths, and evaluate business and architectural trade-offs. You'll act as a technical leader and mentor, driving engineering quality, execution, and decision-making across projects. You'll deploy well-designed, thoroughly tested solutions prioritizing reliability, scalability, and customer impact.
Success means shipping high-quality systems quickly, contributing to foundational platform decisions, improving agent intelligence and reliability, and helping define how AI-powered customer engagement evolves at Klaviyo.
Required: 7+ years software engineering experience, strong full-stack capabilities (front-end and back-end), proven track record building scalable customer-facing systems in fast-moving environments, experience leading projects and mentoring team members, curiosity about AI-native product development with practical LLM or agentic workflow experience.
Nice to have: Python and React expertise, conversational AI or workflow engine experience, retrieval systems and LLM orchestration knowledge, AWS cloud-native development, customer support/commerce/marketing software background, machine learning systems experience, multi-tenant SaaS platform building, observability and AI evaluation tooling familiarity.
