AI Engineer Intern (Summer 2027)

At Klaviyo, we believe the future of software lies not in productivity tools for human users but in software that can run and optimize itself based on outcome or reward metrics. We’ve built the infrastructure and application that serve as the interface between businesses and consumers. We now have over 167,000 customers, billions of consumer profiles, and hundreds of billions of customer messages and follow-on conversion data. We have a big opportunity to build state-of-the-art AI and machine learning technologies at Klaviyo to power our products and develop AI agents that can automatically create and execute marketing or customer experiences, strategies, and campaigns for any business.

At Klaviyo, our Engineering team builds the foundational technologies that power how brands grow through owned marketing. As an AI Engineering Intern at Klaviyo, you’ll play a key role in designing and building scalable backend systems and user experiences that power our AI products and AI agent solutions. You’ll partner closely with product managers, machine learning engineers, and data scientists, to drive real-world impact at scale. This is a backend-heavy role with opportunities to influence architecture, async processing pipelines, distributed systems, and more.

This internship is an opportunity to apply your generative AI and agentic AI application skills in a production environment. You’ll be embedded within one of our engineering teams and work on meaningful projects that help customers interact with powerful marketing tools, all while building a strong technical foundation and connections across Klaviyo.

Interns come to Klaviyo with experience in a variety of technical skills, but they are all passionate about building, owning and scaling features end-to-end from scratch and breaking through any obstacle or technical challenge in their way. As an AI-first company you will be encouraged to use AI tools to support your work, accelerate learning, and succeed in your role.

• Design and build backend systems that support scaling our AI solutions for 200K+ customers.
• Develop robust, reliable and scalable services to serve AI models in production environments.
• Contribute to evolving our agentic architecture — making our AI agents more self-sufficient and performant.
• Contribute to a culture of ownership, experimentation, and customer-centric product thinking.
• Engage with internal stakeholders to understand their needs and resolve blockers.
• Stay abreast of emerging AI trends and technologies, identifying and leveraging opportunities for their application within Klaviyo’s ecosystem.
• Work with the team on project planning and defining achievements, identifying dependencies, and meeting business goals.

• Previous internship experience in AI, machine learning, or related fields, with a strong interest in building and deploying AI projects.
• Have hands-on experience building and deploying generative AI and agentic AI applications into production.
• Demonstrate practical experience with key components of agentic architectures, including orchestration, evaluation, retrieval-augmented generation (RAG), and safety guardrails.
• Proficient in Python and modern backend frameworks (FastAPI, Django preferred).
• Experience creating human and automated evals to ensure high AI model quality.
• Able to thrive in a fast-moving, startup-like environment.

• Trained ML models in the past and deployed them in production systems to generate impact to businesses
• Experience in reinforcement learning
• Experience with large-scale data processing tools including Spark.
• Experience building large scale backend systems

• Our Summer Internship Program is an 11-week paid experience [June 1–August 13] at our Boston, MA headquarters. Interns are in office 5 days a week.
• Offers will be team agnostic - interns are placed on a team approximately 30 days from the start of the program. Team placement can be on a full-stack, back-end, or front-end team within any of the pillars.
• Before joining individual teams, all interns go through Klaviyo Base Camp, our onboarding experience built to get you up to speed on Klaviyo, our product, and the day-to-day of engineering here, plus time to get to know the other interns. You'll join your team ready to dive into real project work from day one.
• Our Boston office is genuinely fun. Lunch is on us 5 days a week, along with free snacks and drinks, ping pong, Nintendo Switch, a golf simulator, and a speakeasy to unwind in.
• Throughout the summer, interns get together for social events beyond team and project work: a Red Sox game, a Boston Harbor Cruise, trips to Kings and Versus, ice cream socials, and Ask Me Anything sessions with Klaviyo's senior leadership.
• Apply before October 11 if you can. We interview and hire on a rolling basis.

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. 

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.