Senior Full Stack Engineer, Customer Agent (AI) | Klaviyo

Klaviyo is looking for a Senior Full Stack Engineer to help build Customer Agent, its AI-native conversational platform. You will shape how autonomous service, AI-driven support, and agentic commerce experiences evolve at scale across millions of customer interactions. The Customer Agent team is building an extensible AI platform that lets brands deliver personalized, autonomous experiences across channels like chat, email, and SMS. The team operates like a startup inside Klaviyo, with high ownership, fast iteration, and a strong bias toward execution.

Key Responsibilities

• Design, build, and scale systems across the stack that power intelligent workflows, conversational experiences, tool integrations, retrieval systems, onboarding flows, observability, and multi-channel engagement
• Develop foundational platform capabilities and customer-facing experiences that let brands launch, customize, and continuously improve their own configurable AI agents
• Tackle complex technical and product challenges, develop multiple solution paths, and weigh business and architectural trade-offs
• Act as a technical leader and mentor, driving engineering quality, execution, and decision-making across projects
• Deploy well-designed, thoroughly tested solutions that prioritize reliability, scalability, and customer impact
• Collaborate with engineering, product, design, data science, and go-to-market teams, and think holistically about customer outcomes
• Contribute to foundational platform decisions and improve the intelligence and reliability of agent experiences

Requirements

• 7+ years of experience in a software engineering role
• Proven track record of building high-quality products and systems, with clean, maintainable code
• Strong experience developing end-to-end solutions, or extensive experience across front-end and back-end technologies
• Experience building scalable, customer-facing systems in fast-moving product environments
• Experience leading projects and being accountable for technical and business outcomes
• Experience mentoring team members or driving initiatives that help the team grow
• Experience conducting code reviews and maintaining a robust testing and deployment cycle
• Curiosity about AI-native product development, including practical experience with LLMs, AI tooling, or agentic workflows in professional or personal projects
• Strong product mindset and willingness to collaborate across functions to solve ambiguous problems with urgency and pragmatism
• Education: Not specified

Skills

Technical Skills

• Full-stack development (front-end and back-end)
• LLMs, AI tooling, and agentic workflows
• Scalable, customer-facing systems
• Code review, testing, and deployment practices

Soft Skills

• Technical leadership and mentoring
• Ownership and accountability
• Cross-functional collaboration
• Product mindset and pragmatism

Nice to Have

• Python and related technologies
• React and related technologies
• Experience building conversational AI systems, workflow engines, or agentic platforms
• Experience with retrieval systems, embeddings, eval frameworks, or LLM orchestration patterns
• Experience building cloud-native solutions, ideally on AWS
• Experience with customer support, commerce, marketing, or customer data software
• Experience with machine learning systems or AI infrastructure
• Experience building multi-tenant or highly configurable SaaS platforms
• Familiarity with observability, tracing, experimentation, or AI quality and evaluation tooling

Benefits

• Total compensation may include an annual cash bonus, equity, and sign-on payments, depending on eligibility
• Comprehensive health, welfare, and wellbeing benefits