Senior Software Engineer - Devx

Location: Boston

This job is with Klaviyo, an inclusive employer and a member of my Gwork – the largest global platform for the LGBTQ+ business community. Please do not contact the recruiter directly.

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  to see how we empower creators to own their own destiny.

Klaviyo is growing fast and we have openings for all skill levels across all of our teams. Learn more about our engineering culture at (Use the "Apply for this Job" box below)..tech

We love tackling tough engineering problems and look for Engineers who specialize in certain areas but are passionate about building, owning & scaling features end to end from scratch and breaking through any obstacle or technical challenge in their way. We push each other to move out of our comfort zone, learn new technologies and work hard to ensure each day is better than the last.

Klaviyo operates a real-time data platform coded in Python built for massive scale on Amazon Web Services (AWS). Engineers come to Klaviyo with experience in a variety of languages and from a number of disciplines.

Team Overview:

DevX is a hybrid product–platform team focused on empowering external developers and partners by supporting applications they build on top of Klaviyo’s Public APIs and features. Examples of these areas of ownership include:

our Application directory, which is used to promote and allow Klaviyo customers to discover applications that they can enable for their account

the self-serve application process for a Partner to submit an Application and the ability for Klaviyo staff to review and approve an Application

API Analytics is a system used by developers and partners to diagnose issues in their applications and understand their API usage. It is powered by a near real–time data pipeline that processes over 160,000 events per second.

Autogenerated API docs, SDKs, CLIs & MCP servers

Responsibilities:

You will have an opportunity to make a major impact on the direction and priorities of the team.

As an engineer on this team, you will work on Klaviyo’s app marketplace, application publishing workflows, and the developer-facing tools and systems that support our app ecosystem. Additional responsibilities include providing quality PR reviews for our code-owned areas of the application, collaborating with product owners and providing technical expertise on upcoming Product Specifications, and participating in the definition of well-defined, estimated, and planned scopes of work.

Required Skills:

5+ years of experience in a software engineering discipline

Experience with full stack application development

Experience working with both monolithic and microservices architectures

Experience with CI/CD pipelines

Experience debugging performance issues and improving application performance

Team Tech Stack:

Python

Django REST Framework, Django, fastAPI

React, React Query

MySQL / postgreSQL

Document DB

Clickhouse

JSON Forms

Redis

Memcached

Rabbit

MQ / Celery / Apache Pulsar

Preferred

Skills:

Experience working with Service Oriented Architecture (preferably in Python)

Experience working with RESTful applications/APIs/gRPC

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

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.…