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Senior Software Engineer - Internationalisation

  • London, UK
  • Engineering

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 by leaps and bounds; as a result, we’ve recently established our Internationalisation team!

The Internationalisation team focuses on enabling every engineer at Klaviyo to write, test, and deploy frontend code as efficiently and easily as possible. While other teams are focused on shipping specific product features to Klaviyo customers, we focus on the underlying infrastructure they use and frontend problems that impact Klaviyo as a whole.

This particular position is an opportunity to help establish the foundation for how we will internationalise our product. 

We are looking to learn from you and leverage your past experience contributing to the internationalisation of a complex SaaS product in a multi team environment.

How you will make a difference:

  • Help design, build, and maintain a robust frontend system to make internationalisation integrated throughout the software development lifecycle. The code you write will help empower an organisation of 300+ engineers (and counting) ship frontend changes faster and more safely.
  • Mentor the engineering team at large on how to write frontend code effectively, with a focus on internationalisation patterns.

Who You Are:

  • An experienced engineer who has developed in and expanded on an internationalised complex SaaS product using React.
  • 2+ years of professional experience with React.
  • Strong knowledge of vanilla JS, ES2015+ syntax, and the Javascript ecosystem as a whole.
  • Familiar with HTML, CSS, and general web best practices.
  • Comfortable working across different parts of a large codebase.
  • Highly collaborative and communicative.
  • Authorisation to work in the UK without restriction.

Bonus points for:

  • Experience with Typescript.
  • Experience with custom frontend build systems + tooling (e.g. Webpack, Babel, TypeScript, ESLint, Jest, Jenkins, CDNs, etc.).
  • Developing application APIs (e.g. REST, GraphQL, JSON Schema, or JSON:API, etc).
  • Having established best practices in how a company writes, tests, and deploys frontend code.
  • Constantly thinking about frontend performance. If shaving kilobytes off a JS bundle or fixing wasted renders sounds appealing, we want to hear from you.

Klaviyo in EMEA;

London was our first non-US location for Klaviyo, opening up in 2019 and growing since then to a large team of people with teams across Sales, Customer Success, Marketing, Services, Partnerships, IT and HR. Collectively in EMEA we are contributing a significant part of Klaviyo’s overall global success, growth to date and opportunity that lies ahead. The good news is that we are still at a stage where everyone coming into the business has the opportunity to make a real tangible impact that you will be able to see and feel.

We are proud of everything we have built here in EMEA, a vibrant diverse team embracing hybrid working in line with the way the world of work has changed. When Klaviyos do travel to the office you’ll be able to use your monthly commuter allowance if you need it. Once here you'll be able to enjoy the comforts of an incredible environment with all the perks we love and you’d expect such as, free snacks / drinks, a peloton studio and a roof terrace overlooking the city to rival anything you’d find in London as well as regular team celebrations and company lunches.

As part of the Klaviyo team you will be looked after with some great benefits locally in EMEA including equity for all, private health cover for you and discounted for your household, financial and professional coaching, a generous annual learning allowance (£2.5k), 22 weeks full pay primary care giver leave (16 week secondary) and free books (yes, any books!) to name a few.

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.

Upon request, you can receive additional information about the compensation and benefits for this role. Requests can be submitted here . Additional information regarding benefits can be found at .

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.

You can find our Job Applicant Privacy Notice here .

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