Senior Software Engineer, Customer Agent

About The Role Our team is looking for a Senior Full Stack Engineer to help build the future of Customer Agent, Klaviyo’s AI‑native conversational platform. In this role, you’ll play a critical part in shaping how autonomous service, AI‑driven support, and agentic commerce experiences evolve at scale across millions of customer interactions. You’ll work across the stack to design, build, and scale systems that power intelligent workflows, conversational experiences, tool integrations, retrieval systems, onboarding flows, observability, and multi‑channel customer engagement. You’ll help develop both foundational platform capabilities and customer‑facing experiences that enable brands to launch, customize, and continuously improve their own highly‑configurable AI agents. As a Senior Engineer, you’ll tackle complex technical and product challenges, develop multiple solution paths, and evaluate business and architectural trade‑offs to determine the best approach. You’ll also act as a technical leader and mentor, driving engineering quality, execution, and decision‑making across projects. Additionally, you’ll be responsible for deploying well‑designed, thoroughly tested solutions that prioritize reliability, scalability, and customer impact. Success in this role means shipping high‑quality systems quickly, contributing to foundational platform decisions, improving the intelligence and reliability of our agent experiences, and helping define how AI‑powered customer engagement evolves at Klaviyo. What We’re Looking For A proven track record of building high‑quality products and systems, with pride in writing clean, maintainable, high‑quality code. 7+ years of experience in a software engineering role. Strong experience developing end‑to‑end software solutions or extensive experience across both front‑end and back‑end technologies. Experience building scalable, customer‑facing systems in fast‑moving product environments – we operate like a startup inside of Klaviyo. Experience leading projects and being accountable for technical and business outcomes. Experience mentoring team members or driving initiatives that help the team grow and learn new skills. Experience conducting code reviews and maintaining a robust testing and deployment cycle. Curiosity and enthusiasm for AI‑native product development, including practical experience experimenting with LLMs, AI tooling, or agentic workflows in professional or personal projects. Excitement about leveraging AI to improve engineering velocity, customer experiences, and operational workflows. A strong product mindset and willingness to collaborate cross‑functionally to solve ambiguous problems with urgency and pragmatism. Nice to Have Skills with Python and related technologies. Skills with 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 with AWS. Experience developing customer support, commerce, marketing, or customer data software solutions. 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/evaluation tooling. Massachusetts Applicants It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability. Compensation & Benefits Our salary range reflects the cost of labor across various U.S. geographic markets. The range displayed below reflects the minimum and maximum target salaries for the position across all our U.S. locations. The base salary offered for this position is determined by several factors, including the applicant’s job‑related skills, relevant experience, education or training, and work location. Base Pay Range For U.S. Locations: $148,000—$222,000 USD In addition to base salary, our total compensation package may include participation in the company’s annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign‑on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility. This role may require up to 10% travel for purposes such as new hire onboarding, client or partner work if applicable, team meetings, and industry events. Travel is coordinated in advance. Equal Opportunity & Non‑Discrimination Klaviyo is committed to a policy of equal opportunity and non‑discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law. #J-18808-Ljbffr Klaviyo