Senior Ai Frontend Engineer Barcelona

We are a product team within Leadtech's AI-LAB. Our job is to research, prototype, develop, launch and scale challenging AI products across the Leadtech portfolio. We're looking for a Senior AI Frontend Engineer who can launch a product and scale it: someone with experience in UX/UI design, A/B testing and product metrics, and who incorporates AI-native tools by default. This is a frontend-first role with full-stack reach. What You Will Do Take new products from zero to launch and beyond. You'll be involved from ideation and research through prototyping, build, release and scale, owning features end-to-end. Prototype fast. Turn a concept into something users can click within days, put it in front of them, and double down or discard it based on what you learn. Scale what works. Once a product finds traction, you'll grow it: hardening the codebase for a larger user base, keeping performance and quality high as scope expands, and evolving features based on how real users behave. Own the frontend: architecture, component library, design system, and the UX that make a great product. Design and build high-converting landing pages, checkout flows and paywalls. You'll work on the surfaces where revenue happens, achieving the best conversion will be part of your job. Bring AI into the development process itself. You'll design and integrate LLM-powered features into our products as well as create skills, automations and internal tooling that make the team faster. Ship to learn. Proactively instrument features, run experiments, read the funnel data, and iterate based on what you discover. You treat metrics as a compass. What You Will Bring 5+ years of frontend engineering, with deep TypeScript and React proficiency (Hooks, Context API, state management, Vite, Tailwind, Shadcn UI) and a track record of owning significant surface area. You have taste. You can distinguish between good and bad UX, articulate why, and share examples from your own work to demonstrate it. You're comfortable in Figma and you hold opinions on typography, spacing and motion. Craft fundamentals. Design systems and component APIs built to last, responsive and mobile-first layouts, accessibility and frontend performance work across bundle size. You build for the long run. You know the difference between a prototype and code that survives a growing user base, and you can tell which one a given moment calls for. You're AI-native in practice. You use AI throughout your development process by default, you've built your own skills, agents or automations to remove repetitive work. Conversion literacy. You've worked on marketing sites, landing pages or checkout flows and understand what drives conversion: hierarchy, friction, trust signals, above-the-fold decisions. You've run or interpreted A/B tests and can distinguish a real result from noise. Solid backend foundations. Node.js, Express, REST APIs and PostgreSQL. You can build the endpoint you need rather than wait for it. You're autonomous and highly collaborative. Given an ambiguous problem, you return with a plan, decisions made and questions surfaced early. You also communicate clearly, give and take feedback well, and work comfortably with people outside engineering. You're self-driven and business-aware. You care about solving real problems and moving the needle on metrics, not just shipping features. Bonus Points Previous experience launching and scaling products in a startup, venture studio or internal product team. Hands-on SEO experience: technical audits, SSR/SSG rendering strategy (Next.js), structured data, international and multi-market pages. Familiarity with experimentation and analytics tooling (Amplitude, GA4). Experience with LLM engineering: prompt tuning, RAG pipelines, vector databases, or agentic frameworks. A genuine passion for AI and a habit of staying on the frontier: new models, protocols, and developer tooling. Benefits WHY LEADTECH Diversified app portfolio with millions of active users in a high-growth non-gaming vertical. Mature data infrastructure: BigQuery, Looker, AppsFlyer, and a proprietary analytics stack for fast decision-making. Experimentation culture: real autonomy to propose and ship changes in production. International team, dynamic environment, and the opportunity for direct P&L impact. Competitive compensation package + benefits (flexible hours, health insurance, training). Growth and career development At Leadtech, we prioritize your growth. Enjoy a flexible career path with personalized internal training and an annual budget for external learning opportunities. Work-Life balance Benefit from a flexible schedule with flextime and the option of working full remote or from our Barcelona office. Enjoy free Friday afternoons with a 7-hour workday, plus a 35-hour workweek in July and August so you can savor summer! Comprehensive benefits Competitive salary, full-time permanent contract, and top-tier private health insurance (including dental and psychological services). 25 days of vacation plus your birthday off, with flexible vacation options—no blackout days! Unique Perks If you wish to come, in our office in Barcelona you’ll find it complete with free coffee, fresh fruit, snacks, a game room, and a rooftop terrace with stunning Mediterranean views. Additional benefits include ticket restaurant and nursery vouchers, paid directly from your gross salary. Join us in an environment where you’re free to innovate, learn, and grow alongside passionate professionals. At Leadtech, you’ll tackle exciting challenges and be part of a vibrant team dedicated to delivering exceptional user experiences Sounds good? Apply now! We’re looking forward to getting to know you. Equal Employment Opportunity Employer: Leadtech is an Equal Employment Opportunity (EEO) Employer, which means we encourage applications from people with different backgrounds, interests, and personal circumstances. Our team welcomes applicants regardless of their race, gender, age, religion, nationality, sexual orientation, gender identity, gender expressión and/or disabilities. All we need is your high energy, skills, and willingness to be a part of a great project! Location You'll have the flexibility to choose whether you'd like to come to the office every day, from time to time, or work fully remote. We want you to find the best combination for you. If you prefer to be surrounded with amazing people, our exceptional office is in Barcelona’s Blue Building, located right on the city's seafront. Besides our stunning views, you’ll enjoy our office perks such as free fruit, snacks, and coffee and you’ll also be able to take part in our Mario Kart and table tennis competitions. Apply to this job LinkedIn login required Cancel * I agree to JobFluent's Terms of Use and Privacy Policy Offer not available? Let us know! Read full job description Read full job description LinkedIn login required * I agree to JobFluent's Terms of Use and Privacy Policy About Leadtech Website https://leadtech.com/ Industry Agency Type Tech Start-up Headquarters Barcelona Company Size 50-200 Founded 2007 At Leadtech, we work hard... and play harder! Our mission is to empower clients and employees to achieve its goals in the online business world. Since 2007, we have been fostering innovative and creative techniques across a multitude of industries, making us pioneers in online project management. Leadtech is dedicated to constant improvement, as well as inspiring new ideas and methods daily, for both the world in which we live and the future to come. We think big... and work bigger, and that's why we do business internationally with over 100 passionate professionals who speak over 15 languages fluently. A global team of focused experts in a range of fields: We analyze, we socialize, we write, we code, we design, we calculate, we decide, we collaborate, we generate, we engage, we program, we create… The real question is what don’t we do?! With a truly modern approach to company culture, our values, diversity, flexibility and an active work-play balance are what make Leadtech unique. Other frontend developer jobs that might interest you... 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