Senior Software Engineer, Composer AI Product

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

Job summary

Klaviyo is seeking a Senior Engineer for the Composer team to help build and scale an AI-powered, in-app conversational platform used by 170,000+ brands. You will own end-to-end software solutions, mentor colleagues, and drive architectural decisions that improve reliability and speed.

Ideal candidates bring 7+ years of software experience, strong front-end and back-end skills, and a passion for AI-native product development.

Qualifications

• 7+ years of experience in a software engineering role.
• Proven track record building high-quality products and systems.
• Experience delivering end-to-end software solutions across front-end and back-end.
• Experience mentoring team members and driving initiatives for growth.
• Experience conducting code reviews and maintaining robust testing and deployment cycles.
• Interest in AI-native product development and practical exposure to LLMs or agentic workflows.

Responsibilities

• Build and ship high-quality, scalable software systems for Klaviyo's Autonomous Marketing platform.
• Provide technical leadership and mentoring across projects, driving quality and pragmatism.
• Contribute to architectural decisions and trade-offs to improve engineering velocity and customer impact.

Skills

7+ years experience

End-to-end software

Front-end & back-end

AI-native product development

Technical leadership

Code reviews & testing

Mentoring teammates

Tools

Python

React

AWS

LLM tooling

Job description

At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyo (we call ourselves Klaviyos) brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you’re a close but not exact match with the description, we hope you’ll still consider applying. Want to learn more about life at Klaviyo? Visit klaviyo.com/careers to see how we empower creators to own their own destiny.

About The Role

The Klaviyo Composer team is building the foundation for how Klaviyo customers plan, create, edit, and iterate on their marketing strategy through an in‑app, AI‑powered conversational experience. We own the native chat surface, the agent orchestrator, and the agentic UI framework that other teams across Klaviyo will plug into. By joining the Klaviyo Conversational AI Platform team, you will have the opportunity to have a direct impact on over 170,000 brands that use Klaviyo every day to engage with their customers. You’ll also help define and build Klaviyo’s Autonomous Marketing platform: an ecosystem of LLM‑powered agents that can analyze, create, and optimize marketing programs across campaigns, flows, forms, and more. As a Senior Engineer, you’ll tackle complex technical and product challenges, develop multiple solution paths, and evaluate business and architectural trade-offs to determine the best approach. You’ll also act as a technical leader and mentor, driving engineering quality, execution, and decision-making across projects. Additionally, you’ll be responsible for deploying well‑designed, thoroughly tested solutions that prioritize reliability, scalability, and customer impact. Success in this role means shipping high‑quality systems quickly, contributing to foundational platform decisions, improving the intelligence and reliability of our agent experiences, and helping define how AI‑powered customer engagement evolves at Klaviyo.

What We’re Looking For

• A proven track record of building high-quality products and systems, with pride in writing clean, maintainable, high-quality code.
• 7+ years of experience in a software engineering role.
• Strong experience developing end-to-end software solutions or extensive experience across both front-end and back-end technologies.
• Experience building scalable, customer-facing systems in fast-moving product environments - we operate like a startup inside of Klaviyo.
• Experience leading projects and being accountable for technical and business outcomes.Experience mentoring team members or driving initiatives that help the team grow and learn new skills.
• Experience conducting code reviews and maintaining a robust testing and deployment cycle.
• Curiosity and enthusiasm for AI-native product development, including practical experience experimenting with LLMs, AI tooling, or agentic workflows in professional or personal projects.
• Excitement about leveraging AI to improve engineering velocity, customer experiences, and operational workflows.
• A strong product mindset and willingness to collaborate cross-functionally to solve ambiguous problems with urgency and pragmatism.

Nice to Have

• Skills with Python and related technologies.
• Skills with React and related technologies.
• Experience building conversational AI systems, workflow engines, or agentic platforms.
• Experience with retrieval systems, embeddings, eval frameworks, or LLM orchestration patterns.
• Experience building cloud-native solutions, ideally with AWS.
• Experience developing customer support, commerce, marketing, or customer data software solutions.
• Experience with machine learning systems or AI infrastructure.
• Experience building multi-tenant or highly configurable SaaS platforms.
• Familiarity with observability, tracing, experimentation, or AI quality/evaluation tooling.

Massachusetts Applicants

It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability.

Our salary range reflects the cost of labor across various U.S. geographic markets. The range displayed below reflects the minimum and maximum target salaries for the position across all our US locations. The base salary offered for this position is determined by several factors, including the applicant’s job-related skills, relevant experience, education or training, and work location.

In addition to base salary, our total compensation package may include participation in the company’s annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign‑on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility.

Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process.

Base Pay Range For US Locations:

$148,000—$222,000 USD

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.

Get to Know Klaviyo

We’re Klaviyo (pronounced clay‑vee‑oh). We empower creators to own their destiny by making first‑party data accessible and actionable like never before. We see limitless potential for the technology we’re developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators—ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you’re ready to do the best work of your career, where you’ll be welcomed as your whole self from day one and supported with generous benefits, we hope you’ll join us.

AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human‑in‑the‑loop). We provide accommodations as needed.

By participating in Klaviyo’s interview process, you acknowledge that you have read, understood, and will adhere to our Guidelines for using AI in the Klaviyo interview Process. For more information about how we process your personal data, see our Job Applicant Privacy Notice.

Klaviyo is committed to a policy of equal opportunity and non-discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law.

You can find our Job Applicant Privacy Notice here and here (FR).