Klaviyo Senior Software Engineer at Klaviyo to lead technical initiatives across internal platforms and AI-powered automation. Own end-to-end lifecycle of multi-team projects impacting thousands of users.
Responsibilities
Our team is looking for a Senior Full Stack Engineer to lead key initiatives that will enhance our product offerings and support our company’s growth. In this role, you'll play a crucial part in shaping outcomes by developing innovative end-to-end solutions using both front-end and back-end technologies. You’ll optimize existing products and create new solutions that redefine what’s possible for our customers.
As a Senior Engineer, you’ll tackle complex challenges, develop multiple solutions, and evaluate business and technical trade-offs to determine the best path forward. You’ll also act as a leader and mentor, and drive key technology decisions. Additionally, you’ll be responsible for deploying well-designed, thoroughly tested solutions that ensure reliability and performance.
Customer Hub is an entrepreneurial team pioneering one of Klaviyo's boldest bets: reinventing how ecommerce brands personalize the shopper journey. We're bringing personalization on-site, building a unified account experience for shoppers across every touchpoint, and turning that into measurable conversion lift. As a nimble group with a fast-moving culture, we prioritize simplicity, speed, and impact. Every team member is expected to take radical ownership—rolling up their sleeves, collaborating across disciplines, and pushing beyond traditional role boundaries to make things happen. Success in this role means delivering exceptional work that sets the standard for velocity and results company-wide, while helping shape Klaviyo’s future through experimentation, creativity, and executional excellence.
Qualification
BA or BS Degree in Computer ScienceYou own mistakes openlyDeep experience building internal toolsTechnologies We UsePython / Django / FastAPITypeScript / React
Required
You are passionate about building software effectively and for the long term, balancing technical quality, velocity, and business impact, and you are comfortable making and explaining trade-offs at that intersection across multiple teams.
BA or BS Degree in Computer Science, related field, or equivalent experience.
12+ years of experience in software development with deep knowledge of computer science fundamentals, domain-driven design, and architectural patterns for distributed, multi-tenant systems.
You bring deep expertise in a core problem space — internal platforms, full-stack or backend SaaS systems, data and event pipelines, web applications, or AI-enabled systems — and you maintain strong system-level thinking across interconnected areas.
You have independently led delivery of large, multi-team programs spanning multiple quarters, including discovery, design, implementation, rollout, and ongoing ownership, and have a track record of breaking through technical obstacles and leading teams through crises by working alongside them in the trenches.
You are comfortable making high-judgment architectural calls in ambiguous situations and committing decisively even when facing disagreement, and you use prototypes and reference implementations to de-risk decisions before broader investment.
You have demonstrated experience defining technical strategy and roadmaps that align with company priorities, integrating input from cross-functional partners, and influencing the roadmaps of adjacent teams whose work intersects with yours.
You have a track record of redirecting teams from low-value approaches toward higher-leverage solutions, and of building patterns, processes, and reference implementations that multiply team effectiveness with measurable, multiplicative impact.
You are an AI-native engineer and leader. You regularly use modern AI tools — coding assistants, LLM APIs and SDKs, agentic workflows, RAG pipelines, and evaluation harnesses — to accelerate your engineering workflow, you have practical experience building or integrating AI-powered systems, and you are excited to set the standard for how an organization adopts AI thoughtfully and responsibly.
You take direct ownership of operational excellence for the systems your teams build, including performance, reliability, observability, security, cost, and on-call, and you are comfortable defining SLOs, leading incident response, and owning RCAs end-to-end.
You are highly effective at working through influence and delegation. You provide clear technical direction, create the clarity, patterns, and guardrails that let a large group of engineers move quickly and safely, and you are an exceptional communicator across technical and non-technical audiences.
You own mistakes openly, take action to prevent recurrence, and share learnings broadly so the wider organization benefits from what your team has learned.
Preferred
Deep experience building internal tools, developer platforms, or operations automation, with measurable impact on reliability, productivity, or operational efficiency across multiple teams.
Practical experience building or integrating production AI systems and agents, including workflows using LLM APIs and SDKs, agentic or automated workflows, RAG pipelines, evaluation harnesses, and monitoring frameworks for AI systems.
Experience designing and operating large-scale services on AWS with infrastructure as code (Terraform) and containerized environments (Kubernetes), including capacity planning, cost optimization, and disaster recovery.
Experience partnering closely with go-to-market, customer service & support, finance, or operations leaders to translate complex workflows into internal tools that drive measurable efficiency and business outcomes.
Technologies We Use
Klaviyo’s platform is primarily built with Python and React and runs on AWS. Engineers join us from a wide range of technical backgrounds and are supported in learning our stack. Core technologies include:
