Lead Engineer, Applied AI (Customer Agent)

About the Team

Our Engineering team builds the AI systems that power how brands run their businesses on Klaviyo. We move fast, ship in production, and hold a high bar for what "AI-native" actually means: systems that make real judgment calls, not demos.

The Customer Agent team is one of the newest and most ambitious groups in that org, based in Boston and working in-office: we're building a conversational AI system that lets brands serve their own customers at a scale no human support team could match. We ship changes against live customer traffic, measure quality with real evaluation frameworks, and treat reliability as a product feature.

About the Role

As Lead Engineer, you'll set the technical and product direction for a core area of Customer Agent end to end, building a 0-to-1 agentic product with the speed and ownership of a startup, backed by the scale and resources of Klaviyo, while staying hands-on with the hardest problems yourself. This lead role features a wide footprint across our agentic product—from orchestration to governance—that grows based on where the product is when you join.

How You'll Make an Impact

• Set the technical and product direction for a core area of Customer Agent, from architecture through production, and contribute to the direction of the platform overall.
• Take on the hardest technical problems in your area: orchestration, evaluation, guardrails, memory & context, failure handling for non-deterministic systems.
• Write and ship code, review designs, and make the hard calls in your area when there’s no obvious right answer.
• Define patterns that other engineers adopt, and mentor through design reviews rather than direct management.
• Partner with product, design, data science, and go-to-market leaders to shape what gets built, not just how it’s built.
• Evaluate emerging AI technologies and bring the ones worth betting on into production.

What We're Looking For

• Experience building, scaling, and supporting production agentic systems (not just prototypes): orchestration, evals, guardrails, and non-deterministic failure handling through launch, incidents, and operational reality.
• Learned operational lessons from running agents in production: securing them against misuse and abuse, and maintaining reliability as usage grows.
• Track record of owning technical and product direction for a significant area that shipped and served as a foundation for other engineers.
• Hands-on engineering approach: writing code, reviewing architecture decisions, and debugging production issues.
• Proven reuse of your patterns and designs across engineering teams.
• Ability to communicate complex technical trade-offs across engineering and product audiences, turning undefined problems into plans.

Nice to Haves

• Experience working on a multi-tenant agent platform at production scale.
• Experience building 0-to-1 products or working in startup environments.
• Track record with production evaluation systems, AI observability, or human-in-the-loop workflows for LLM-powered products.

Additional Details

• Role is based in-office in Boston, MA.
• May require up to 10% travel for onboarding, client/partner work, team meetings, and industry events.