Sr. Lead Software Engineer - Messaging Infrastructure

Klaviyo is a leading marketing automation platform that helps businesses grow by delivering personalized experiences. As a Senior Lead Software Engineer within the Messaging Infra organization, you will serve as the primary technical architect for high-volume message delivery systems and drive the technical vision for channel expansion.

Responsibilities:

• Define the technical strategy and architectural vision for the Messaging Infra platform, ensuring all system improvements align with long-term business goals for massive scalability, high reliability, and low latency message delivery
• Serve as the primary architect to build and improve high-volume message delivery systems across multiple channels, focusing on throughput, performance, and reliability
• Drive technical leadership to guide architectural decisions across multiple teams, striving towards a cohesive technical vision across multiple roadmap items and providing solutions for complex problems around scalability and performance
• Oversee and execute the planning and seamless rollout of major software releases and updates for the platform, managing the entire lifecycle from design to deployment in production environments including significant individual contributions
• Act as a go-to expert for diagnosing and resolving complex performance, scalability, and reliability issues across the messaging platform. Implement proactive monitoring and telemetry to identify and address problems before they become critical incidents
• Mentor other engineers regularly, primarily experienced lead and senior engineers, to develop new technical leadership for the company
• Partner with product managers, deliverability and compliance specialists, and other stakeholders to gather requirements, resolve conflicts, and ensure alignment across all teams and projects
• Stay current with emerging technologies and industry trends, evaluating new tools and practices to identify how they can improve systems and internal processes

Requirements:

• 12 years of experience in software development, strong knowledge of computer science fundamentals, domain-driven design, and extensive expertise in architectural patterns, specifically within the domain of distributed systems
• Have proven that you can build and scale complex distributed systems, including solving problems in sustainable ways, balancing pragmatic development with ideal architecture, breaking through technical obstacles with vigor, and leading teams through crises by working side by side with them in the trenches
• BA or BS Degree in Computer Science, related field, or equivalent experience
• Technical Expertise: Deep expertise in relevant programming languages (e.g., Python, Go) and cloud platforms (AWS, Azure, GCP), containerization (Kubernetes, Docker), and Infrastructure as Code (Terraform). You are particularly passionate and an expert in multiple stack areas, with strong and opinionated experience with various technologies, and know how to pick the right tool for any job
• Technical Strategy: Demonstrated experience in contributing to the product and platform vision, as well as defining the strategy within the broader scope of long-term organizational needs
• Architectural Skills: Strong understanding of software architecture, design patterns, and system integration, with the ability to define technical strategies and influence architectural decisions across multiple teams
• Soft Skills: Exceptional problem-solving, analytical, leadership, and communication skills, with the ability to articulate complex technical concepts to both technical and non-technical audiences
• AI Enthusiast: You've already experimented with AI in work or personal projects, and you're excited to dive in and learn fast. You're hungry to responsibly explore new AI tools and workflows, finding ways to make your work smarter and more efficiently
• Experience with the email and/or SMS ecosystem, including understanding of channel-specific protocols and security specifications (e.g., DKIM, DMARC, SPF), and familiarity with key 3rd-party entities (like mailbox providers, anti-abuse groups, and telecoms) and compliance rules/best practices
• Background in performance optimization and a passion for digging into performance and scalability issues to drive breakthrough solutions
• Familiarity with complex data management for testing, including large datasets and production-like data replication