At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyo (we call ourselves Klaviyos) brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you’re a close but not exact match with the description, we hope you’ll still consider applying. Want to learn more about life at Klaviyo? Visit klaviyo.com/careers to see how we empower creators to own their own destiny.Team Overview The Amplify Engineering team builds the internal tools, platforms, and AI-powered automation that help Klaviyos work more efficiently and at scale as the company grows. We partner across the organization, including Sales, Marketing, Engineering & Product, and Customer Service & Success, to solve real operational problems with practical, well-designed software. Our work spans internal applications, 3rd-party integrations, interactive dashboards, CMS integrations, and robust AI systems and agents that automate repetitive tasks, surface the right information at the right time, and help teams make better decisions. We operate in tight feedback loops with our internal customers, shipping quickly, learning fast, and seeing the impact of our work immediately in how deals move faster, tickets resolve sooner, and launches go more smoothly. This role is for senior technical leaders who own hard problems end-to-end across multiple domains, set the technical bar for how Amplify builds, and drive engineering excellence across the broader organization. The work is highly visible and has a direct impact on how thousands of Klaviyos get their work done every day. How You’ll Make an Impact The Amplify team builds the internal platforms, automation, and AI-driven systems that power how Klaviyos work every day. As a Senior Lead Software Engineer on Amplify, you will: Independently own and drive high-impact objectives that span multiple Amplify teams and align with company priorities, defining the technical roadmap that ensures our internal applications, APIs, data and event pipelines, and AI-powered workflows can scale with Klaviyo and continue delivering measurable business outcomes. Be accountable, in partnership with Engineering Managers, for the long-term technical health of Amplify’s systems — quality, reliability, scalability, cost, and security — across a significant slice of Klaviyo engineering, maintaining strong system-level thinking across interconnected internal platforms. Independently lead the end-to-end lifecycle of large, multi-team initiatives with clear technical direction, architectural leadership, and active workstream curation, from discovery and design through implementation, rollout, and long-term ownership of complex programs that span internal customers across the company. Make high-judgment architectural calls in ambiguous situations, committing decisively even when facing disagreement, and use prototypes and reference implementations to de-risk decisions before broader investment. Establish shared standards, patterns, and reference implementations that multiply team effectiveness across Amplify and adjacent engineering teams, and proactively redirect efforts away from low-leverage approaches and toward higher-impact solutions when projects are off-course. Define and communicate forward-looking technical strategy that integrates input from Product, Design, Data, and operational partners, and use that strategy to lead technical discussions and influence the roadmaps of adjacent teams whose work intersects with Amplify. Set the standard for AI-native engineering at Amplify. Use modern AI tools — coding assistants, agentic workflows, RAG pipelines, and evaluation harnesses — as a core part of your day-to-day workflow, define guardrails for building AI-powered systems responsibly, and help the broader engineering organization adopt AI effectively in design, coding, testing, and operations. Own the response to complex performance, scalability, and reliability issues across Amplify systems, working side by side with teams in the trenches during incidents, owning mistakes, and turning post-incident learnings into changes that prevent recurrence and raise the bar across the organization. Define and own the operational standards Amplify holds itself to, including SLOs, monitoring and alerting, incident response, security, observability, and cost, and continuously evolve them as usage and complexity grow. Get work done primarily through influence, delegation, and clarity, providing clear technical direction and creating the patterns, platforms, and de-risked references that let dozens of engineers across Amplify move quickly and safely. Invest in the growth of engineers across levels at Amplify, with a particular focus on developing emerging Senior and Lead engineers through design reviews, pairing, RFC feedback, and intentional one-on-one coaching, and participate actively in senior engineering hiring to represent Klaviyo’s technical challenges and culture. Connect technical work to customer outcomes and business objectives, ensuring Amplify is investing in the highest-leverage opportunities and that engineering practices advance with measurable, multiplicative impact across the organization. Who You Are 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. You are passionate about mentorship and have direct experience growing senior engineers and leads, including emerging Seniors and Leads, through design reviews, technical coaching, and creating opportunities for others to step up. You participate actively in senior engineering hiring. You enjoy questioning convention and continuously improving how things work — architecture, tooling, workflows, or processes — and you know how to introduce change while bringing people along with you. You enjoy working in small, autonomous, agile teams, shipping incrementally, and partnering closely with product, data, and design partners to deliver better outcomes for internal customers. Nice to Have 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: Python / Django / FastAPI TypeScript / React MySQL / Redis / Memcached RabbitMQ / Celery / Apache Kafka / Apache Pulsar AWS / Terraform / Kubernetes AI: Anthropic, OpenAI, and Google Models. Claude Code & Cursor Location & Work Model This role is based in Boston, Massachusetts and follows a hybrid working model. Klaviyo supports work authorization and relocation for this position. At Klaviyo, we enjoy tackling meaningful engineering challenges and value people who take ownership, learn continuously, and collaborate openly. We are committed to building inclusive teams and encourage applications from candidates of all backgrounds. Klaviyo is growing fast and we have openings for all skill levels across all of our teams. Learn more about our engineering culture at https://klaviyo.techMassachusetts 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. 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 US 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. 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. Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process.Base Pay Range For US Locations:$216,000—$324,000 USDThis 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. Get to Know Klaviyo We’re Klaviyo (pronounced clay-vee-oh). We empower creators to own their destiny by making first-party data accessible and actionable like never before. We see limitless potential for the technology we’re developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators—ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you’re ready to do the best work of your career, where you’ll be welcomed as your whole self from day one and supported with generous benefits, we hope you’ll join us. AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human-in-the-loop). We provide accommodations as needed. By participating in Klaviyo’s interview process, you acknowledge that you have read, understood, and will adhere to our Guidelines for using AI in the Klaviyo interview Process. For more information about how we process your personal data, see our Job Applicant Privacy Notice. 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. IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses (@klaviyo.com), instant messaging platforms, or unsolicited calls. 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