Senior Frontend Engineer - with an interest in fullstack

Cardlay A/S; København; Hybrid; DKK 700,000 - 1,000,000; Full time

Benefits offered by this job

Hybrid work from Copenhagen or Odense

Company-paid phone

Home internet

Lunch, coffee, fruit, drinks and in‑k-

Job summary

Cardlay is a Danish fintech building white-label card and spend management solutions. Our web portal lets companies run cards, expenses, accounting and people management with their own brand.

As Senior Frontend Engineer, you own the frontend of our web portal, drive architectural decisions, build reusable components, and mentor peers. You will work closely with Product and our UI/UX Lead, reporting to the Head of Engineering, with hybrid work from Copenhagen or Odense.

Qualifications

• Deep experience with React and TypeScript.
• Shipped complex features in a web product that customers rely on.
• Experience building or contributing to a design system or component library.
• Familiar with AI-assisted coding tools and best practices.

Responsibilities

• Own the frontend of Cardlay's web portal, ensuring quality, performance and direction.
• Make key frontend decisions on architecture, design system scope and migrations.
• Drive projects from idea to production with Product and UI/UX Lead; own them end-to-end.
• Build reusable components and patterns as part of product work; avoid one-off solutions.
• Migrate legacy screens to the design system, preventing visual regressions.
• Define component APIs, lint rules and documentation to guide AI-generated code.
• Mentor engineers, share knowledge through reviews, docs and pairing.

Skills

Frontend leadership

Mentoring teammates

UX awareness

Tools

React

TypeScript

Vite

pnpm

MUI

styled-components

Storybook

TanStack Query

TanStack Table

Redux Toolkit

React Hook Form

react-intl

Vitest

MSW

Cypress

Biome

Job description

Senior Frontend Engineer - with an interest in fullstack

Cardlay is a Danish fintech building white-label card and spend management solutions. Banks, issuers and financial partners in Europe and the US offer our platform to their business customers using their own brand.

We are a small dedicated team with short decision paths. We make bold decisions, turn them into results by helping each other, and give people the mandate to own what they build.

About the job

About Cardlay

Cardlay is a Danish fintech building white-label card and spend management solutions. Banks, issuers and financial partners in Europe and the US offer our platform to their business customers using their own brand.

We are a small dedicated team with short decision paths. We make bold decisions, turn them into results by helping each other, and give people the mandate to own what they build.

About the job

Our web portal is where companies run their spend: cards, expenses, accounting and people management. Every bank offers it under its own brand.

Some of the core capabilities include

• Cards: card programs, card orders and requests, and funding accounts
• Expenses: transactions, receipts, mileages and expense policies
• Accounting: categories, cost dimensions, GL accounts and exports to external accounting systems
• People and teams: onboarding, invitations, roles and company settings

Under the hood, it's React, TypeScript, pnpm workspaces and Vite.

Every new bank brings its own brand and requirements, and AI agents now write a growing share of our code. We need a senior engineer who builds the product and keeps the shared components and patterns behind them consistent, so new screens, whether built by people or AI agents, look and work like the rest of the product.

This is a hands-on product role with significant ownership: you will build features every day and help set our frontend direction.

What success looks like after a year

• Customers use features you built and shipped end to end
• A new feature takes less code and fewer review rounds than it does today
• New screens are built from shared components by default, by people and AI agents alike
• The core libraries are up to date with latest security updates and we are on a clear upgrade path going forward

The challenge

Customers rely on the platform every day, and it has grown over several years:

• Some pages use our new design system and some don't yet. Deciding what to migrate, and when, to keep the experience consistent is ongoing work
• You work closely with our UI/UX Lead. That takes the confidence to push back on designs that hurt the user experience, and the taste to know when you're right
• There are several ways of handling data and state in the codebase, and picking the right one for each case directly affects what customers experience
• We're a small team, and other developers contribute a lot to the web portal. As the senior frontend engineer, you decide what's good enough to merge and where our code style and stack go next
• You look beyond your own domain. When the answer is on the other side of the API, you read the backend code and unblock yourself where you can

What you'll do

As a Senior Frontend Engineer, you will own the frontend of our web portal. You take responsibility for what we ship, make decisions others can build on, drive projects forward and help the people around you grow.

You will be the primary frontend engineer in an engineering team of 10 people across frontend, backend, mobile and DevOps. You will work closely with Product and our UI/UX Lead, and report to our Head of Engineering.

Your responsibilities will include

• Take responsibility for the frontend as a whole: its quality, performance and direction
• Make the key frontend decisions and stand by them: architecture, what goes into the design system and when to say no
• Drive projects from idea to production with Product and our UI/UX Lead, and own them until customers are using them
• Build reusable components and patterns as part of your product work, not one-off solutions
• Move legacy screens onto the design system as you work on them, without silent visual regressions
• Set up component APIs, lint rules and docs so AI agents produce code that fits
• Mentor other engineers and share what you know through reviews, docs and pairing

Who you are

We are looking for an experienced frontend engineer who loves building a product and cares about the quality and consistency behind it.

You likely bring

• Deep experience with React and TypeScript
• You have shipped complex features in a web product that customers rely on
• You use AI coding tools every day and know where they go wrong
• A good eye for UX and product quality
• You speak up when something could be done better, and you see your work through to production
• You have driven projects with other engineers and helped them grow through mentoring and reviews

Bonus if you have

• Experience building component libraries or design systems
• Design tokens or white-label theming
• Interest in fullstack work, so you can help out on the backend when you can
• Experience from fintech or complex B2B products

You will work with the technologies below. We don't expect experience with all of them; we are looking for engineers who learn quickly.

• React, TypeScript
• Vite, pnpm workspaces, Biome
• MUI, styled-components, Storybook
• TanStack Query, TanStack Table, Redux Toolkit
• React Hook Form, react-intl
• Vitest, MSW, Cypress

Why Cardlay

You will join at a point where our platform is proven, our customer base is growing and AI is changing how we build software. You will have a real say in how Cardlay builds the frontend, in a team where senior engineers set the direction.

• Permanent employment, freelance or consultancy, with salary or rate matching experience
• Hybrid work from our offices in Copenhagen or Odense
• English as our main working language, with Danish spoken too. You don't need to speak Danish to join
• Flexible working hours, and the option to work from home when it suits you and the team
• Company-paid phone and home internet
• Lunch, coffee, fruit, drinks and snacks at the office

Any questions about the position can be directed to our Head of Engineering:

Magnus Biolzi Hansen, Mail: [e-mail] , Telephone: [phone]

Application deadline: We review applications as they come in and will close the position once we've found the right person.