Sr. Lead Backend Engineer - Marketing AI Platform

At Klaviyo, we empower over 200,000 global businesses to convert first-party consumer data into actionable, personalized engagement. As we advance our Marketing AI and Service AI initiatives, we are building intelligent systems capable of running, optimizing, and adapting complex workflows autonomously based on real-time outcome signals.

As a Sr. Lead Software Engineer in the Orchestrate Pillar, you will architect and scale Klaviyo’s core orchestration engine—the high-throughput, low-latency platform that executes high-volume marketing workflows across billions of consumer profiles. In this principal-level technical leadership role, you will bridge heavy distributed systems engineering with AI-native methodologies—integrating LLMs, agentic workflows, and RAG pipelines directly into our core backend services while maintaining strict Tier-1 availability and performance standards.

Key Responsibilities

• Platform Architecture & Scaling: Architect and scale the Core Orchestration platform, supporting high-traffic, asynchronous event processing with low latency and high availability.
• AI & Agentic Systems Integration: Drive technical strategy for embedding agentic workflows, LLM decision engines, and RAG pipelines into real-time customer marketing interactions.
• AI-Native Engineering Leadership: Lead the adoption of modern AI-native software development workflows across the engineering org to shorten feedback loops and accelerate delivery speed.
• Foundational Frameworks & Mentorship: Design core backend frameworks and microservices adopted across engineering teams, raising engineering rigor via design reviews, architectural guidance, and mentorship.
• Cross-Functional Strategy: Partner with Product Management, Data Science, Design, and Executive leaders to shape long-range technical roadmaps, platform boundaries, and business goals.
• Quality, Observability & Evals: Build robust evaluation frameworks for production AI models, managing trade-offs across inference latency, output accuracy, cost, and safety.

Requirements

Distributed Systems & AI Engineering Depth

• 8+ years of professional software engineering experience centered on distributed systems, microservices architecture, and high-availability backend platform ownership.
• Agentic AI & LLMs in Production: Practical experience shipping production LLM workflows, retrieval-augmented generation (RAG) pipelines, or agentic frameworks, with solid grounding in evaluations, prompt architectures, and fine-tuning.
• High-Throughput Distributed Infrastructure: Proven track record building asynchronous processing pipelines, event-driven architectures, and messaging queues (Kafka, Celery, SQS, Redis).
• Python Expertise: Deep proficiency in Python and modern frameworks (FastAPI, Django), data processing platforms, and ORM tools.
• Cloud Infrastructure & DevOps: Strong expertise with AWS, Kubernetes, Docker, CI/CD automation pipelines, and modern observability suites (Datadog, OpenTelemetry).
• AI-First Workflow: Active daily use of AI development tools and agentic coding workflows to write, test, and optimize software.

Work Logistics

• Ability to work in-office at Klaviyo’s headquarters in Boston, MA under our hub-first workplace model.

Preferred Qualifications

• Experience designing, building, or integrating shared AI/ML platform microservices consumed by multiple internal engineering teams.
• Domain expertise in MarTech, e-commerce platforms, real-time personalization engines, or event-streaming infrastructure at scale.

Total Rewards & Benefits

• Compensation & Equity: Base salary of $216,000 – $324,000 USD + participation in annual cash bonus plan + competitive equity grants.
• Comprehensive Healthcare: Robust medical, dental, and vision insurance options for employees and eligible dependents.
• Financial Security & Retirement: 401(k) retirement savings plan, life insurance, and disability coverage.
• Workplace Culture & Perks: Onsite collaboration at Boston HQ, professional development stipends, and dedicated AI productivity tool access.