Senior Full-Stack Engineer — AI Platform, Equity

Klaviyo; Boston (MA); On-site; USD 148,000 - 222,000; Full time

Job summary

Klaviyo is seeking a Senior Full Stack Engineer to help build the future of our AI-native Customer Agent platform. You will design, implement, and scale systems across frontend and backend to power autonomous service and multi-channel engagement for millions of customer interactions.

You’ll mentor colleagues, drive quality, and explore AI tooling and LLM integration, collaborating with product, design, data science, and GTM teams to ship reliable, scalable solutions.

Qualifications

• 7+ years in a software engineering role.
• Experience front-end and back-end development.
• Experience building scalable, customer-facing systems.
• Experience leading projects and mentoring teammates.
• Experience with code reviews and robust testing/deployment.
• Curiosity for AI-native product development and LLMs.
• Strong product mindset and cross-functional collaboration.

Responsibilities

• Design, build, and scale systems powering intelligent workflows and multi-channel engagement.
• Develop foundational platform capabilities and customer-facing experiences.
• Mentor teammates and drive engineering quality and decision‑making.
• Ship high-quality, reliable, scalable systems prioritizing customer impact.
• Collaborate across engineering, product, design, data science, and GTM teams.

Skills

Full stack

Front-end & back-end

AI-native development

Mentoring

Code reviews

Observability/Deployment

Cross-functional collaboration

Tools

Python

React

AWS

Job description

Klaviyo is seeking a Senior Full Stack Engineer to help build the future of our AI-native Customer Agent platform. You will design, implement, and scale systems across frontend and backend to power autonomous service and multi-channel engagement for millions of customer interactions.

You’ll mentor colleagues, drive quality, and explore AI tooling and LLM integration, collaborating with product, design, data science, and GTM teams to ship reliable, scalable solutions.