Senior Lead AI Engineer - Agentic Systems & LLMs NEW

The Briefed; Boston (MA); On-site; USD 216,000 - 324,000; Full time

Benefits offered by this job

Competitive pay

Healthcare

401(k)

Onsite HQ

Dev/learning stipends

Job summary

Klaviyo is seeking a Senior Lead Engineer for the Customer Agent team in Boston. You will define technical direction for a 0-to-1 conversational AI platform, architecting end-to-end systems and solving hard production challenges while staying hands-on in codebase.

You will mentor engineers, collaborate with PMs, Data Science, and GTM, and contribute to AI tooling, guardrails, and scalable evaluation frameworks on a multi-tenant platform.

Qualifications

• Demonstrated track record as a Principal or Senior Lead Engineer having architected, built, scaled, and operated a production agentic system end-to-end.
• Hands-on experience solving operational challenges in production: non-deterministic failures, prompt injection defense, context window optimization.
• Proven experience setting product-level technical strategy and building shared frameworks adopted across teams.
• Hands-On Coding & Execution: active involvement in writing production code, reviewing design decisions, debugging live production issues.
• Outstanding technical communication skills to convey AI trade-offs to exec, product, and engineering audiences.

Responsibilities

• Technical & Product Architecture: set end-to-end tech direction for the Customer Agent platform into production-ready architectural blueprints.
• Hands-On Core Engineering: personally write and review architecture, debug production incidents.
• Agentic Infrastructure: design orchestration engines, context memory stores, guardrails, and evaluation frameworks.
• Cross-Functional Alignment: partner with Product, Design, Data Science and Go-to-Market leaders to shape the roadmap and product vision.
• Mentorship: build reusable frameworks and mentor senior engineers through design reviews.
• Emerging AI Technology Evaluation: evaluate frontier LLM models and AI tools, integrating high-value advancements into production.

Skills

Agentic AI systems

Production-grade software

Architectural design

Hands-on coding

Technical communication

Job description

At Klaviyo, we empower global brands and e-commerce creators to make first-party data actionable. Our Applied AI group builds production-grade, AI-native systems that handle real business judgment calls for tens of thousands of customer-facing brands.

As a Senior Lead Engineer on the Customer Agent team, you will set the technical and product direction for a 0-to-1 conversational AI agent platform that enables brands to deliver autonomous customer support at massive scale. This is a principal-caliber individual contributor role for a hands‑on engineer who has personally architected, deployed, and scaled production agentic systems past the demo stage. Operating in an in-office environment in Boston, you will solve the platform’s hardest non-deterministic engineering challenges—including agent orchestration, real-time evaluation frameworks, safety guardrails, context management, and self-healing mechanisms—while remaining actively hands‑on in the codebase.

Key Responsibilities

• Technical & Product Architecture: Set end-to‑end technical direction for the Customer Agent platform, converting ambiguous problem spaces into production‑ready architectural blueprints.
• Hands‑On Core Engineering: Solve complex non‑deterministic system problems personally—writing clean code, conducting architectural design reviews, and debugging production incidents.
• Agentic Infrastructure: Architect robust orchestration engines, context memory stores, LLM guardrails, failure‑handling mechanisms, and automated evaluation frameworks.
• Cross‑Functional Alignment: Partner directly with Product Management, Design, Data Science, and Go‑to‑Market leaders to shape the strategic roadmap and product vision.
• Force Multiplier & Mentorship: Build reusable frameworks and platform abstractions that other engineering teams adopt; mentor senior engineers through technical guidance and design reviews rather than direct line management.
• Emerging AI Technology Evaluation: Continuously evaluate frontier LLM models, agentic frameworks, and AI tools, integrating high‑value advancements directly into production.

Requirements

Deep Agentic & AI Systems Expertise

• Demonstrated track record as a Principal or Senior Lead Engineer having architected, built, scaled, and operated a production agentic system end‑to‑end through launch, scale, and operational incidents.
• Deep, hands‑on experience solving operational challenges unique to running agents in production: non‑deterministic failure handling, prompt injection defense, agent abuse mitigation, and context window optimization.
• Proven experience setting product‑level technical strategy and building shared frameworks/architectures that were adopted across multiple engineering teams.
• Hands‑On Coding & Execution: Active involvement in writing production code, reviewing architecture decisions, and debugging live production issues without delegating core technical challenges.
• Outstanding technical communication skills—ability to convey complex AI trade‑offs clearly to executive, product, and engineering audiences.

Work Logistics

• Ability to work in‑office at Klaviyo’s headquarters in Boston, MA.

Preferred Qualifications

• Experience operating a multi‑tenant agent platform at production scale, where external clients configure custom agent behavior on shared infrastructure.
• Track record in 0-to-1 product development or high‑growth startup engineering environments.
• Practical experience with production evaluation systems (evals), AI observability pipelines, and human‑in‑the‑loop (HITL) workflows for LLM‑powered products.

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.