Senior Software Engineer - Ventures Team

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.
Ventures is where Klaviyo builds new products that are adjacent to the core business. We seek to leverage data, automation and scale to deliver our customers more powerful and integrated experiences.
This is a high visibility, high impact role with ample opportunity for growth. You will build mission-critical features inside a new team and product. You will define new engineering practices, code infrastructure and other primitives that ensure the success of Klaviyo Ventures for the long run.
Why you should join Klaviyo Ventures
Do you want to build a startup inside a much bigger startup?
We're looking for entrepreneurial builders who want to work with a small team to rapidly iterate against new product areas. You will work closely with potential customers to build solutions to key problems they face.
You'll have the autonomy to move fast and get a product from zero to one. And then you will scale it to hundreds of thousands of users.
How you'll make a difference

• Launch a new product as part of a small team exploring new revenue opportunities.
• Be empowered to own the mission, technical direction and operations of projects that have immediate impact
• Advance your technical skills in all facets ranging from front end web development and user experience to machine learning and massively parallelized data pipelines

As a Sr. Full Stack Software Engineer you will collaborate with engineers, designers and a product manager. You'll build amazing new products and experiences that unlock new growth trajectories for Klaviyo.
Who You Are
We are looking for a full-stack engineer with a focus on the front-end. We expect this engineer to have experience using Typescript, React and Python to craft scalable systems.
Candidates for this role should be confident writing production ready code on the client and server in order to build best in class UI/UX experiences. This engineer should be experienced writing their own frontend and backend components, build and/or extend libraries, etc. This role requires writing API endpoints and creating flexible and re-usable data models.
Klaviyo at present has over 143K+ paying customers generating over $50bn+ of Klaviyo Attributed Value (KAV) and it is important we are able to scale inside and outside our customer base. To that end, we expect engineers on our team can build and work with fault tolerant, containerized distributed systems. On the frontend, we expect that you can re-use and create flexible components capable of rendering across browsers & devices with different specs.
At your core, you are:

• Entrepreneurial - You've launched your own companies or side projects or are used to working quickly and iteratively based on customer feedback.
• Empathetic - Experience 1:1 interfacing with customers to help improve your product and process.
• Experienced - 5-7+ years of experience and have architected, built and delivered user-facing features that added business value
• Confident - You are comfortable setting higher-level technical direction and process with the help of peers and senior management. You are comfortable with ambiguity.
• Curious - You enjoy working with new technologies ranging from the frontend to backend and have deep experience in multiple technology stacks. You show this by having strong opinions and experience with various technologies throughout multiple projects. You know how to pick the right tool for any job.

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. Please visit Klaviyo Rewards to find out more about our Total Rewards package.
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.
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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