Front-end Software Engineer Intern (Summer 2026)

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.

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 careers.klaviyo.com to see how we empower creators to own their own destiny.

About our Internship

At Klaviyo, our Engineering team builds the foundational technologies that power how brands grow through owned marketing. As a Front-end Software Engineering Intern, you’ll be part of a fast-paced, collaborative environment where your work directly impacts thousands of customers worldwide. You won’t just be writing code—you’ll be solving real problems, shaping user experiences, and learning from seasoned engineers across our engineering organization.

This internship is an opportunity to apply your React and front-end development skills in a production environment. You’ll be embedded within one of our engineering teams (see overviews below) 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 coding languages, 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.

How You’ll Make an Impact

• Own features that our 150K+ paying customers rely on daily to reach their consumers to drive their business forward
• Build new UI experiences to make complex areas of Klaviyo easier to use.
• Work on foundational areas to help us internationalize Klaviyo, and make it more accessible and performant.
• The code you write will help empower tens of thousands of Klaviyo customers daily to gain more value from the platform.
• Focus on unlocking impact by using the right tools for the job, leaning into AI, and always looking for opportunities to make a meaningful difference

What We’re Looking For

• At least one previous software engineering internship with software development experience
• Currently pursuing a degree in Computer Science, Engineering, Data Science, Math/Statistics or related field 
• Graduating in December 2026 or May/June 2027
• Experience with React
• Experience with some of these technologies and languages:
• Python, React, Django, Celery
• MySQL, Clickhouse, RabbitMQ, Redis
• HTML, Typescript, JavaScrip, CSS
• Amazon Web Services (EC2, RDS, Aurora, etc.) Terraform, Ansible, Packer, and other DevOps tools
• Enjoy working with new technologies and adept at selecting the right tool for any job
• Love digging into performance and scalability issues to drive breakthrough solutions-- whether it's a slow loading UI or too many clicks in a workflow, a database query timing out, or a queue that just won’t drain. You recognize all problems can be solved.
• Enjoy shipping code early & often in an agile fashion, pairing with product management to craft better software by soliciting feedback from thousands of end users
• Embrace Klaviyo’s “always learning” culture that fosters learning at every level, constantly pushing yourself to be a better engineer 

Internship Logistics

• Our Summer Internship Program is an 11-week [June 1 - August 14] paid experience at our Boston, MA headquarters. Interns are required to be in office 5 days a week.
• Before diving into individual teams and projects, all interns will complete Klaviyo Base Camp - our customized onboarding experience. Base Camp provides focused time to learn about Klaviyo, our product, the ins and outs of engineering and spend time getting to know other interns. This robust training experience ensures all interns join their teams fully prepared to dive into project work and make an immediate impact. 
• Our Boston office is fun - our interns stay fueled with free snacks and drinks, take breaks with each other over a game of ping pong, Nintendo, or a round of golf with our simulator, and relax in our speakeasy (yes you read that right!).
• Throughout the summer, Klaviyo interns attend social events to promote interaction beyond team and project work. In past years these events have included a Red Sox game, outings to Versus and Flight Club in the Boston Seaport, ice cream socials, and Ask Me Anything sessions with Klaviyo senior leadership.
• It is highly recommended that you apply prior to October 11 as we interview and hire on a rolling basis 

Engineering at Klaviyo

At Klaviyo our engineering teams are broken into pillars to streamline the work.  

Growth: Reduce friction across the board for our customers, increase cross-sells, and help us launch into new geographies and verticals

Marketing Platform: Give marketers the tools they need to engage with their customers, be successful, and know where they stand

Mobile Channels and Messaging Infrastructure: Own the growth of our mobile channels and all messaging infrastructure

Data Infrastructure: Empower our internal teams and customers to get the best out of our data and underlying capabilities

Core Infrastructure: Empower our internal engineering, sales, and service teams to be as effective as possible

We use Covey as part of our hiring and / or promotional process. For jobs or candidates in NYC, certain features may qualify it as an AEDT. As part of the evaluation process we provide Covey with job requirements and candidate submitted applications. We began using Covey Scout for Inbound on April 3, 2025.

Please see the independent bias audit report covering our use of Covey here

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.

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.