Lead Software Engineer, Messaging Infrastructure

Requirements

• 8+ years of engineering experience with strong backend and distributed systems design skills
• Proficient in Python and/or Go, and able to pick up the other quickly
• Experienced with large-scale system architecture — familiar with the tradeoffs involved and able to apply them against real business constraints
• Comfortable contributing to architecture and code directly; this is a hands-on role
• Skilled in scaling infrastructure on AWS
• Strong product and business mindset — you think beyond the code to understand customer impact
• Self-directed and delivery-focused — you ship incremental value and iterate
• Clear communicator who thrives in a high-autonomy, cross-functional environment
• You've already experimented with AI in your work or personal projects and are excited to keep pushing on that

What you'll be doing

• Own and drive the architecture of key components in Klaviyo's messaging pipeline — from ingestion and routing through to delivery and status tracking
• Lead a team of engineers building and scaling highly-available, high-throughput services across one or more messaging channels
• Design and implement scalable backend services in Python and/or Go
• Work on a campaign pipeline that processes and delivers hundreds of millions of messages daily, growing to billions-scale
• Bring clarity to ambiguous technical problems — breaking undefined challenges into concrete, actionable plans
• Collaborate across product, deliverability, compliance, and platform teams to expand messaging capabilities
• Drive best practices in system design, code quality, and engineering process across your team
• Mentor and grow engineers, contributing to a high bar across the broader Messaging Infra organization
• Build smarter systems and workflows by putting AI at the center of how you and your team work

Perks and Benefits

• 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.