Ux Ui Designer jobs in Spain

Join Crown as our Founding Lead Developer to lead the development of Crown – and help reinvent ProcureTech in Europe!

Location : Paris, France

Start Date : ASAP

Contract Type : Full-time (CDI or equivalent)

Salary : Based on experience (+ BSPCE equity)

What We’re Building

CROWN MACHINE is a high-performance, AI-powered SaaS platform transforming how companies negotiate through real-time electronic auctions (eAuctions). Now, we’re scaling—and there’s so much still to build. From connecting LLMs and optimization algorithms to refining UX and automation, you’ll join at a pivotal moment where your technical vision and code will shape the platform’s future. Within months, we’ve built a cutting-edge product, onboarded several enterprise clients, closed €1M+ in projected revenue, and raised our first round from top-tier VCs like Kima Ventures, Heartfelt, and Prequel.

Who We Are

Crown was founded by Mykyta Voytenko , an eProcurement expert with 15+ years at Nestlé, Sanofi, and Engie. We’re a passionate, international team of 10, blending deep procurement expertise with startup speed and tech ambition. Joining now means becoming part of the founding team — where your contributions will shape the future of B2B negotiation tech.

As Lead (founding) Developer , you’ll own the architecture, performance, and scalability of our full-stack platform. You’ll lead technical decisions, and drive the next phase of product development with a strong focus on real-time systems, data privacy, and seamless user experience. Today, the platform is live and running real-time eAuctions with enterprise clients, but the most exciting work is ahead : enhancing scalability, expanding eAuction logic, and bringing in smarter decision-support features. We're also laying the groundwork for smarter automation and decision-making, leveraging data and AI where it creates real value. You’ll play a central role in bringing these capabilities to life.

• Frontend : Nuxt.js 3 (Vue.js), Vuetify
• Backend : Nuxt.js 3 (Nitro)

Responsibilities

Technical Strategy & Architecture (30%)

• Design scalable, secure architecture for high-performance auction systems.
• Define technical roadmap in collaboration with product and ops teams.
• Ensure modular, maintainable code and lead implementation of best practices.

Full-Stack Development (30%)

• Build new features across front and back-end.
• Optimize platform performance, latency, and UX.
• Maintain a high standard of code quality and testing.
• Collaborate closely with our Product Designer and Head of Ops.
• Conduct code reviews, lead sprint planning, and guide technical onboarding.
• Participate in real-time eAuctions.

Security, Deployment & Monitoring (15%)

• Ensure secure handling of sensitive procurement data.
• Maintain DevOps workflows and Vercel deployment.
• Monitor application health, analytics, and performance bottlenecks.

About You

• 4+ years of experience as a full-stack developer (Experience in Vue.js and Node.js mandatory)
• Strong foundation in software architecture and scalable design
• Experience with PostgreSQL / Supabase and serverless environments
• You care deeply about performance, security, and product experience
• Comfortable working autonomously in a fast-paced startup
• Experience leading or mentoring developers

Bonus Points

• Experience with Nuxt.js, Vuetify, Supabase, and real-time application architecture
• Previous exposure to B2B SaaS or procurement / marketplace products
• Interest in AI-driven tooling and procurement automation

Our Hiring Process

• Application & Pre-Selection → Send us your CV and a short motivation note.
• Intro Chat → 30-minute conversation with our Chief of Staff.
• Technical Questionnaire → A few async questions and a mini case.
• Deep-Dive Interview → 30-60-minute session with the current Tech Team who developed the app.
• Meet the Team → Informal chat with Crown’s crew.
• References & Decision → We move fast and give you clear, actionable feedback.

Learn More About Crown

LinkedIn

Website

Demo

Ready to build the future of eProcurement?

Join us and shape a platform used by some of Europe’s top industrials.