Senior Software Engineer - SMS Delivery

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.
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
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. geographic markets. The range displayed below reflects the minimum and maximum target salaries for the position across all our US locations. The base salary offered for this position is determined by several factors, including the applicant's job-related skills, relevant experience, education or training, and work location.
In addition to base salary, our total compensation package may include participation in the company's annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign-on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility.
Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process.
Base Pay Range For US Locations:
$152,000 - $228,000 USD
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.
AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human-in-the-loop). We provide accommodations as needed.
By participating in Klaviyo's interview process, you acknowledge that you have read, understood, and will adhere to our Guidelines for using AI in the Klaviyo interview Process . For more information about how we process your personal data, see our Job Applicant Privacy Notice .
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.
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