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Klaviyo is seeking a Senior Full Stack Engineer to help build Customer Agent, an AI-native conversational platform that powers autonomous service, AI-driven support, and agentic commerce experiences at scale. 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 strong execution bias. Every engineer is expected to think holistically about customer outcomes, collaborate deeply across engineering, product, design, data science, and go-to-market teams, and push beyond traditional role boundaries.
As a Senior Engineer, 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.
Required: 7+ years software engineering experience, proven track record building high-quality products and systems, strong end-to-end or full-stack development experience, experience building scalable customer-facing systems in fast-moving environments, experience leading projects and being accountable for technical and business outcomes, mentoring experience, code review and testing expertise, curiosity about AI-native product development with practical LLM or agentic workflow experience, strong product mindset and cross-functional collaboration skills.
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.
