Senior Software Engineer - LLMs & Agentic Commerce

Klaviyo empowers over 100,000 creators and businesses to own their destiny by making first-party customer data accessible and actionable across e-commerce and digital marketing.

As a Senior Software Engineer on the Applied AI (Customer Agent) team, you will help build the future of Customer Agent—Klaviyo’s AI-native conversational platform. You will work across the full stack to design, scale, and deploy systems that power autonomous customer service, conversational experiences, retrieval systems, tool integrations, LLM evaluations, and multi-channel customer engagement across chat, email, and SMS. Operating with startup-like velocity inside Klaviyo, you will lead complex technical initiatives, evaluate architectural trade-offs, mentor engineers, and ship production-grade AI platforms that enable brands to launch and customize their own intelligent AI agents.

Key Responsibilities

• Customer Agent Platform Architecture: Architect, build, and scale extensible end-to-end systems for Klaviyo's conversational AI platform, powering autonomous support, tool integrations, and agentic workflows across chat, SMS, and email.
• LLM & Agentic Workflows: Design and implement agentic orchestration patterns, prompt/context pipelines, embeddings, retrieval-augmented generation (RAG), and automated evaluation/observability frameworks.
• Full-Stack Execution: Deliver high-quality full-stack software solutions spanning frontend interfaces (React/TypeScript) and backend microservices (Python/Django, AWS).
• Technical Leadership & Mentorship: Drive engineering quality, code reviews, architectural standards, and testing best practices while mentoring team members to elevate overall team capabilities.
• Cross-Functional Product Ownership: Partner closely with Product Management, Design, Data Science, and Go-To-Market teams to turn ambiguous business needs into scalable technical specifications and customer-facing features.
• Operational Excellence: Maintain robust CI/CD deployment pipelines, system observability, tracing, and unit/integration testing to ensure high platform reliability at scale.

Requirements

Software Engineering & Applied AI Depth

• 7+ years of professional software engineering experience building and maintaining complex, production-grade systems.
• Full-Stack / Backend Engineering Depth: Demonstrated success developing scalable customer-facing software end-to-end, with strength across both backend services and frontend architectures.
• Technical Leadership & Delivery: Proven track record of leading multi-week technical projects, establishing architectural designs, and taking end-to-end accountability for business outcomes.
• AI & LLM Curiosity: Practical experience experimenting with or building with Large Language Models (LLMs), AI tooling, RAG, or agentic workflows in production or professional projects.
• Engineering Quality & Mentorship: Deep experience conducting thorough code reviews, mentoring junior engineers, and maintaining automated testing/deployment pipelines.
• Product Mindset: Strong product intuition with a bias toward execution and rapid iteration in fast-moving product environments.

Work Logistics

• Ability to work remotely from within the United States.

Preferred Qualifications

• Strong proficiency in Python and React / TypeScript.
• Hands-on experience building conversational AI platforms, LLM orchestration frameworks, workflow engines, or agentic systems.
• Experience with retrieval architectures, vector databases, embeddings, or LLM evaluation frameworks.
• Background in cloud-native AWS infrastructure, multi-tenant SaaS architectures, or e-commerce/customer support software.
• Experience with AI observability, tracing (e.g., LangSmith, Phoenix), or experimentation tooling.

Total Rewards & Benefits

• Compensation & Equity: Base salary range of $148,000 – $222,000 USD + annual performance cash bonus + equity compensation package.
• Healthcare & Wellbeing: Comprehensive medical, dental, and vision insurance options, plus dedicated health and wellbeing stipends.
• Flexible Remote Work: Fully remote working model with up to 10% coordinated travel for team offsites and industry events.