Full-Stack Developer (m/f/d)

What we do

Imagine every product on the internet, instantly available to you. You could take anything from any online shop, resell it, and earn from it. You could spend your Payback points or miles on something you actually want, instead of another forgettable knife set. And your AI could buy any product in the world for you, without your intervention.

We built exactly that. It's live, and it's running today.

Joy_'s AI infrastructure runs the entire e-commerce value chain end to end: sourcing, checkout, payment, fulfillment, customer care, and returns. Across any online shop on the planet. No merchant contracts, no closed networks. This is our Universal Purchasing Infrastructure, and it sits right at the center of where AI commerce is going.

On top of it, we build our own business models. The first one live and proven: the gift card. That is a 20 billion euro market in Germany alone, the single most-gifted thing in the country, and nobody has innovated on it in years. Now there is a gift card you can redeem for any product, from any shop, for any wish.

We've raised from top European funds and angels who have built and scaled some of the most relevant tech and commerce companies around. Behind it all: a team of twelve, spread across Europe, with a strong center and our office in Berlin.

The technology is live. Now we are growing the engineering team that builds on top of it, and the gift card is where you come in.

The role

As a full-stack engineer, you work across the whole gift card product: the screens customers use and the services running behind them. Day to day, you will:

• Own features from discovery to production: You will partner directly with the other teams to scope ideas, design architectures, and ship features - collaborating closely with senior peers while leveraging AI tools to iterate with extreme speed.
• Build and refine the gift card experience, from buying a card to redeeming it.
• Develop the back-end that powers it: APIs, services, and data models.
• Work on the partner side too, the B2B self-serve product and the embeddable widgets that let other companies plug Joy_ in.
• Keep the codebase healthy, with shared components, design tokens, sensible tests, and an eye on performance and accessibility.

What we're looking for

We are not reading your CV for logos or degrees. Show us what you have built and shipped.

• 3+ years building modern web products, full-stack. Genuinely comfortable on both the front-end and the back-end.
• A deep sense of product ownership. You don't wait to be told what each step is. When you see a broken piece, you take it upon yourself to fix it. You care about the product actually working, not just clearing backlog tickets.
• An exceptional teammate. We are a small, tight-knit team. We win together. That means you are someone who proactively communicates, communicates clearly in a remote async environment, enjoys code reviews as a tool for teaching and learning, and leaves your ego at the door.
• An elite execution mindset. You use modern tools (like AI terminal agents) to strip away boilerplate and focus your brainpower on architecture, security, and user delight.
• A real eye for detail. You care deeply about typography, layout, and motion. You can comfortably navigate Figma to extract design intent, tokens, and variables to build polished, pixel-perfect user experiences.
• You think in systems. Data models, API design, and performance are things you weigh up rather than work around.
• A pragmatic approach to quality. Unit and e2e tests where they earn their keep, with steady attention to performance and accessibility.
• Excellent spoken and written English. German is a plus, not a must.

Bonus points for: payments, e-commerce, or loyalty and rewards products; design systems or Storybook; experiments and event analytics.

Our stack

This is the stack you'll work in, in rough order of priority. The essentials come first. The rest is a plus, and we're happy for you to grow into it with us.

Core application development

• TypeScript, the backbone of everything we build.
• Vue.js on the front-end.
• PostgreSQL: relational database design, query optimization, and data modelling.

• Nice to haves (or a strong curiosity to learn):

• Effect-TS for robust error handling and concurrency in TypeScript
• Nuxt.js

AI & Developer Workflows

• Git: For clean version control, branch management, collaborative PR reviews, and team tracking.
• Claude Code & Terminal Agents: We actively encourage using terminal-based AI workflows to navigate, refactor, and write boilerplate code.
• Figma MCP (Model Context Protocol): We utilize MCP servers to bridge our codebase directly with Figma variables, tokens, and layouts for tight design-to-code compilation.

Cloud and infrastructure (Nice to have)

• AWS & Kubernetes: For hosting our containerized services.
• Prometheus & OpenTelemetry: For distributed tracing, monitoring, and alerting across complex system behaviors.

How we think

We think like caring jesters: joyful, kind, clever. We challenge the status quo by staying light on our feet and bold in our ambition. Our compass:

Aesthetics. Efficiency. Joy.

We believe great products come from delight, design, and a little magic, and that the most ambitious technology in the world should still feel human.

What's in it for you

• 🌱 Real responsibility. You work across the whole product and sit close to the founders every day.
• 🚀 Growth. Build on the frontier of AI commerce alongside senior operators and engineers who have scaled before.
• 💡 Autonomy. Remote-first, with the freedom to work how you work best.
• 🎁 Meaningful equity. We want you to win with us.
• 🛍️ Real impact. Watch what you build go live in front of a whole country. Fast.

Interested?

If this feels like your kind of joyride, we'd love to hear from you. Apply through the form below and attach your GitHub or portfolio, or live product links. No formal cover letter needed.

One question, and it is the only one we ask:

Point us to a product you worked on end to end, front-end and back-end. What state was it in when you started, what did you change, and how did you know it worked?

At Joy_, everyone is welcome. We build with kindness, creativity, and curiosity. What counts is your energy and perspective, not your CV or where you studied. Let's create something joyful together.