Senior Frontend Engineer in London

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About Topsort

Today, Topsort has 6 major hubs worldwide, and employees in 13+ countries, including Menlo Park, Boston, Santiago Chile, São Paulo Brazil, Barcelona Spain, and Sydney Australia. We are a truly global company that was born in the pandemic that has had rapid growth since out of a genius product, a customer‐first mentality, and a hardworking team of talented individuals. Since our founding in 2021, we've gained customers in retail, marketplaces, and delivery apps in 40+ countries and are quickly approaching the #1 position in the industry.

Why Topsort? Why now?

Topsort is changing the way Retail Media works. By joining our scaling team, you'll feel your impact from day 1. The processes and messaging you build today will be a critical part of our foundation as we accelerate toward 200 Topsorters worldwide, and your innovations will leave a lasting mark on the industry, as a whole. Retail Media is on the verge of a new era, and Topsort is gathering the ecosystem together to shape a brighter future. Joining us now, you'll work directly alongside our co‐founders and founding members to bring on Retail Media 3.0. If you're looking to define your career as something greater than yourself, come scale with us.

What it's like to work at Topsort

At Topsort, we communicate openly and move fast. We say things as they are, challenge each other early, and embrace feedback with curiosity—it’s how we build better, faster. Every experiment has a purpose, and every outcome helps us make the next decision smarter. There's no single formula for success here; we find what works, improve it, and scale it. We're collaborative internally and competitive externally—never the other way around. The pace is quick, sometimes a 100‐mph kind of fast, and that's what keeps it exciting. We act with intent, lift each other up, and turn bold ideas into real results. No endless meetings here—if it can be done today, it gets done today.

Senior Front‐End Developer – Role Overview

As a Senior Front‐End Developer at Topsort, you'll be responsible for building and optimizing user‐facing features that power our platform, working closely with designers, product managers, and backend engineers to deliver seamless and responsive web experiences. You'll work primarily with modern JavaScript frameworks like React (and ideally Next.js), focusing on performance, accessibility, and scalability. This role is ideal for someone who thrives in a fast‐paced startup environment, enjoys turning complex problems into intuitive interfaces, and takes pride in clean, maintainable code.

What you will do

• Develop, maintain, and optimize front‐end components and user interfaces.
• Work closely with designers, product managers, and backend developers to implement new features.
• Ensure cross‐browser compatibility and responsive design for web applications.

What We Think You Need to Be Successful

We're open to candidates who don't check every box but show strong potential.

Core Requirements & Experience

• Bachelor's in Computer Science, Design, or related field.
• 5+ years of experience in front‐end development.
• Strong knowledge of JavaScript, HTML, CSS, and front‐end frameworks such as React.
• Proficiency in modern JavaScript frameworks (React, Vue.js, or similar).
• Experience with front‐end build tools and workflows (Webpack, Babel, NPM).
• Strong understanding of responsive design, accessibility, and web performance optimization.

Preferred experience:

• Experience with Next.js or server‐side rendering (SSR).
• Contributions to open‐source projects or development of high‐traffic web applications.

Bonus Points

• Demonstrated experience working in a three‐tier application architecture.
• Experience working with Python frameworks like FastAPI.
• Experience working with PostgreSQL.

What We Value

• Deep dive into details: Professionals who are not content with superficial answers and dive deeply into the details to uncover root causes and optimal solutions.
• Team first: A low need for individual recognition, always prioritising collective results over personal credit.
• You thrive with ambiguity: Exceptional ability to tackle open‐ended problems in unstructured environments, turning chaos into structured innovation.
• Adaptability: Willingness to learn, mentor, lead, and follow as the situation demands, fostering growth at all levels.
• Urgency: A disproportionate sense of urgency in execution, while keeping scalability and the creation of replicable processes in mind to ensure long‐term success.
• Curiosity: Genuinely curious individuals who can quickly learn difficult concepts and apply them effectively.

We are proud to be an equal opportunity employer and to foster a workplace where diversity is valued and celebrated. We believe that diverse perspectives and experiences strengthen our teams and drive better outcomes. We respect and value any race, religion, color, national origin, ancestry, caste, gender, gender identity or expression, sexual orientation, age, disability, medical condition, pregnancy, genetic information, marital status, or military service.

Do you sound like the right fit? Let's dive right in!