Senior Fullstack Engineer

🪐 Discover our galaxy Join the Future of Work ! Keystone AI is Europe's leading freelance marketplace, connecting over 1,000,000 talented freelancers with 100,000+ companies. Founded in 2013, we're transforming how work gets done through our tech-powered, human-centered platform. What makes us different: - A diverse team of 600 Keystone AI ers across 6 European countries - A culture that champions equality (50% of our Comex are women) and inclusive growth - Backed by top investors including ISAI, Serena Capital, Eurazeo Growth, Goldman Sachs, and BPI - A mission to give everyone the freedom to work differently Ready to help shape the future of work? Your next chapter starts here! 🪐 Key responsibilities ✨ Think product-first : You’ll work hand-in-hand with Product Managers and Designers to deeply understand user needs, challenge ideas, and co-create elegant solutions. You like to be part of the decision-making, not only execute what has been specced. Take the lead : You’ll own your features end-to-end. From first sketch to release (and beyond). You’re empowered to make decisions and trusted to do what’s right for the product. Build smart, ship fast : We deploy to production around 70 times a week. You’ll help us keep that rhythm by balancing speed, quality, and business impact. Be a partner, not an executor : You bring strong opinions, backed by experience and you’re not afraid to challenge the status quo when it makes sense. Level up the team : You share knowledge, put in place pair programming when it’s needed, review code with care, and bring others along on your journey. You help raise the bar. Our Tech Stack Frontend : TypeScript, Vue.js, Nuxt, Internal Design System , Stencil.js Backend: Kotlin, Java Spring Boot, Gradle, PostgreSQL, MongoDB, Elasticsearch, RabbitMQ, Redis Platform : Google Cloud Platform, Kubernetes, Terraform, ArgoCD, Gitlab CI The AI Toolkit : We empower our devs with modern AI coding assistants and are building internal workflows and investigating as many uses as possible (docs, unit tests, migrations) Data : BigQuery, dbt, Looker, Spark, Python Life @ Keystone AI Remote Culture : Strong remote culture with most of the team working full-remote from countries where Keystone AI has a physical office and legal entity (France, Germany, Spain, Belgium, Netherlands, or UK). Tech Days : 15% of engineering time dedicated to technical project, , continuous training and learning, R&D and technology watch. Tech Conferences : Annual Product, Tech and Data workshop, annual Keystone AI Tech Days, organized and presented by Keystone AI ’s engineering team. Opportunity to attend major tech conferences. About you 🧑‍🚀 You have 6+ years of professional experience in software development, with a first experience in a product company (SaaS, fintech, marketplace…) You're highly proficient in Java or Kotlin , and comfortable navigating complex backend architecture, APIs, and data models. You have a first experience working with Typescripts and eager to learn Nuxt and Vue.js . You have a “Product Engineer” approach : You think beyond the code. You’re curious about the “why” behind features, and you're proactive in proposing improvements and owning delivery from A to Z. You build with pragmatism : You know how to adapt your practices to the context. You have excellent knowledge of modern architecture, but you also know when you need to move fast and build disposable code. Autonomy : You are committed to improving the team's practices and know how to adapt your methods to suit the context. You own the whole lifecycle : building CI/CD, testing, observability, monitoring. Shipping is just one step. You make sure what you build works, lasts, and scales. Fluent in English , you are comfortable speaking and writing in an English-speaking environment. How to join the mission? 🚀 Screening with Alex , our Talent Acquisition Manager, to better understand your background, aspirations and answer your questions (45 minutes) Interview with one of our Engineering Manager, to discuss your experience and the role in more detail (75 minutes) Technical assignment (homecase or livecase, you choose) to prepare and present in order to evaluate your hard skills (90 minutes) Final interview with Jean (VP Engineering) to discuss Keystone AI ’s long term vision (45 minutes) We will send you an interview guide so you can best prepare yourself. Keystone AI is the perfect space to thrive personally and professionally 💫 - Onboarding: Before easing into your new role, you’ll spend your first week learning about our culture, products, and services with other new joiners at our office in Paris - Equity: Every Keystone AI er is entitled to stock options - Keystone AI sabbatical: Every three years, all Keystone AI ers are entitled to a one month fully paid sabbatical leave - Free books: If you’re interested in learning more about any topic relevant to Keystone AI ’s business, just tell us the books you’d like to read, and we’ll order them for you—without any questions asked or approval processes to follow - Team build