Senior Full Stack Engineer - Sidekick

The Sidekick team builds and owns the progressive web app that SumUps field sales agents rely on every day, a tool that brings together everything a seller needs in one place: creating offers on the go, signing up new merchants, managing hardware sales, and tracking commissions in real time. It's one of our most impactful internal products, sitting at the heart of a primary revenue driver for the business.

As our Senior Full Stack Engineer, you'll take genuine ownership of features end-to-end, from scoping through to production, working closely with product, engaging directly with sales stakeholders, and having a real say in what gets built and why. If you want autonomy, meaningful scope, and work that directly enables the people driving SumUp's growth, this is the role.

What you'll do

Build and maintain features across the full stack of our progressive web app, spanning the field sales experience, back office tooling for sales agents, and emerging LLM-powered support tooling, owning work from scoping through to production

Participate actively in product discovery, joining user research sessions, reviewing usage data, and contributing to prioritisation discussions alongside product

Work directly with sales stakeholders to understand their needs, distinguish between what's requested and what's actually needed, and propose solutions with clear trade-offs

Contribute to raising engineering standards across the team, through documentation, code quality, and proactive process improvements

Integrate with external systems such as Salesforce where required, and help shape how data flows across domains to create a consistent experience for field sellers

You'll be great for this role if

Hands-on experience with a full-stack framework, Next.js, Remix, Nuxt, or similar, with a clear track record of shipping real-world features end-to-end.

Strong, proven experience with React and TypeScript, building scalable, maintainable applications in a production environment.

Expe