Software Engineering Internship - Summer 2025 - Full-stack & Back-end

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 are close but not an 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

Our Software Engineering internship is small. This is purposeful - so we can ensure each intern is able to undertake meaningful and robust projects that directly impact our product and customers. It also creates a tight-knit group of interns who get to bond with each other over the course of the summer.

Interns are valued members of our engineering department, which is made up of small, agile teams that collaborate across Klaviyo to constantly ship work that impacts our product. Interns have ownership over features, while also learning from and connecting with fellow Klaviyos from engineering, product, design, and beyond to make sure they craft the right solutions. We operate a real-time data platform coded in Python built for massive scale on Amazon Web Services (AWS).

We move fast here - interns work on projects at scale and often ship their work during the course of the summer. We offer a supportive environment where interns can test, fail, iterate and launch while building a solid technical foundation, awesome connections across Klaviyo while having fun.

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 obstacles or technical challenges in their way.

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
• Be responsible for the mission, technical direction and operations of projects that have immediate impact
• Architect and design robust and high performance data processing and storage systems leveraging new databases to serve different internal and external use cases
• Craft our highly scalable real-time data pipeline that processes billions of events weekly across data sets growing to petabyte scale
• Work on a deep analytics system that provides insight into hundreds of terabytes of data

What We’re Looking For

• At least one previous software engineering internship/co-op with software development experience
• Graduating in December 2025 or May/June 2026

• Experience with some of these technologies and languages:

  • Python, Django, Celery
  • MySQL, Cassandra, Clickhouse, RabbitMQ, Redis
  • HTML, JavaScript, Typescript, LESS, Backbone.js, React
  • Amazon Web Services (EC2, RDS, Aurora, etc.) Terraform, Ansible, Packer, and other DevOps tools
  • EMR, SageMaker

• Enjoy working with new technologies ranging from the frontend to backend and adept at selecting the right tool for the 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 and 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 paid experience (June 2nd - August 15th) at our Boston, MA headquarters
• Before diving into individual teams and projects, all interns will complete Klaviyo Base Camp - a week+ 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 over a game of ping pong, Nintendo Switch, or a round of golf in our golf 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 Munch n Learns with Klaviyo senior leadership.
• It is highly recommended that you apply prior to October 11th