Senior Software Engineer - SMS Delivery

Why You Should Join the SMS Delivery Team:

The SMS Delivery enables our customers to confidently select the right sender IDs for their marketing needs—and to register and activate those IDs through a single, intuitive, and transparent workflow. The experience is designed to be cross-channel, eliminate redundant data entry, and get customers up and sending messages quickly while meeting defined SLAs. As regulations evolve, we ensure our customers remain fully informed and compliant with all new and changing requirements.

.As a Senior Software Engineer on the team, you’ll play a key role in designing and building scalable systems that power our editor experiences across all the editors. Partnering closely with product managers and technical product owners, you’ll help define scope, translate ideas into practical implementations, and build intuitive editing tools that delight our users. This role leans frontend, with a strong focus on crafting thoughtful, reusable components and seamless user experiences using technologies like React, Python, and Django. There are ample opportunities for growth given the scope of this role and the team’s central role in Klaviyo’s product.

Over the past year, our team has enhanced the managing senders, across multiple channels and incorporating more api driven way to editor interfaces with impactful features that our customers love—and they’re eager to see that same power brought to other mobile experiences. Looking ahead, we’ll be investing in new editor blocks, a personalization builder, in-canvas editing, and content generation powered by AI. You’ll contribute directly to these efforts, helping Klaviyo extend its best-in-class editing tools across platforms.

How You Will Make a Difference:

• You will be a core member of the Editors platform team, working on impactful customer-facing features that will make our product the best in the industry.


• You will work on creating easy-to-use editors that are highly performant.


• You will work closely with Product, Design, and Data Science to provide the best experience for our customers.


• Transform workflows by putting AI at the center, building smarter systems and ways of working from the ground up.

Who You Are:

• Experienced in full-stack development with strong hands-on skills in React, Redux, JavaScript, HTML, and CSS, along with familiarity with general web best practices.


• Proficient in Python and Django (or similar backend technologies), and comfortable working across large codebases and multiple layers of the stack.


• Familiar with automated testing practices and frameworks, including end-to-end and integration tests (e.g., Pytest).


• Experienced with RESTful and GraphQL APIs, and evolving APIs and data models to support product success.


• You take ownership of your work—from requirements and edge cases to implementation and testing—and are motivated by solving tough problems with others.


• Proven track record of leading complex, multi-quarter projects involving cross-team collaboration.


• You know when to reach for tools like queues, caches, CDNs, and web workers to solve performance and scaling challenges.


• Collaborative, communicative, and eager to learn and share knowledge.


• You’ve already experimented with AI in work or personal projects, and you’re excited to dive in and learn fast. You’re hungry to responsibly explore new AI tools and workflows, finding ways to make your work smarter and more efficient.

Technologies We Use (not exhaustive):

• React, TypeScript, Redux


• Python, Django


• MySQL, RabbitMQ, Redis, ProxySQL


• Amazon Web Services (EC2, RDS, Aurora, etc.), Terraform, and other DevOps tools

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