Product Engineer, Experience (Frontend)

bAbout Callimacus /bpAt Callimacus, we're working to change how people interact on the web. For the past 30 years, the user experience as we know it has been anchored to a typographic paradigm — predefined navigation trees of pages, sections, and menus — established in the Nineties when the web was born. /ppAs the way people get informed, entertained, and shop evolves, traditional websites and interfaces are losing relevance, and the tools available limit the creative evolution of digital experiences. Callimacus was born from the conviction that the whole web experience can and should be reinvented. /ppSo we built the engine for a different kind of digital experience. Callimacus is a multi-agentic platform that plugs into a company's existing stack and reads multi-dimensional signals to understand what a visitor wants in the moment. Then, in milliseconds, our proprietary technology composes the entire interface around that intent, selecting the most relevant content and components as the person interacts. /ppCallimacus was founded in 2024 with the early backing of Brunello Cucinelli — one of our first investors, and now one of our customers. We launched in January 2026 to strong organic interest from enterprise customers, and recently raised from Salesforce Ventures the largest AI investment they have made in Italy, and one of their most significant in Europe. /ppWe are a small, product-focused, founder-led team. We work on hard problems that haven't been solved before — by us or anyone else — and the people who join now get to solve them. We move fast, with high agency and strong ownership. /pbWhat you'll build /bpYou'll join a small senior team at the point where the platform's foundations are still being set. Callimacus is in production with demanding customers, and the architecture, the performance envelope, and the shape of the developer experience are all still yours to influence. Decisions you make in your first months will still be load-bearing in three years. /pullibOwn the rendering path. /bThe pipeline that turns composed output into an experience that feels immediate — streaming, hydration, and perceived performance on sites we don't control. /lilibBuild the SDK customers integrate. /bThe TypeScript SDK that drops into enterprise frontends — API design, developer experience, and documentation people actually enjoy using. /lilibDesign the component and composition system. /bInterfaces assembled on the fly by agents still have to feel deliberate and on-brand. You make that true. /lilibSweat the performance envelope. /bCore Web Vitals, bundle discipline, and edge delivery — on our customers' sites, under their traffic. /lilibShape the integration experience. /bFrom first npm install to production, across stacks and frameworks we don't choose. /li /ulbWhat matters to us /bpThese are the same for every role at Callimacus. We hire people who get the job done and care about the end result — the product, the experience, the people using it. /pullibOwnership. /bYou feel deeply responsible for your work and behave accordingly — from design through production and after. You don't wait to be told what to do; you see problems and act. “It's not my job” is not part of your mindset. /lilibInvention. /bYou light up at hard problems and are creative at finding solutions. You experiment, get your hands dirty, and land things. You hold very high standards and always look for ways to improve. /lilibTeam-oriented. /bYou're someone others can count on. You support the best idea even when it's not yours, disagree productively, give and take feedback, share credit, and take on unglamorous work when that's what the team needs. /li /ulpbThe craft bar for this role: /bStrong TypeScript and deep React knowledge, with a track record of shipping polished production frontends. You treat developer experience as a product surface, not an afterthought. /pbWhere you might be strong /bpWe're early, and nobody is strong in all of these — we don't expect you to be. Depth in two or three, plus curiosity about the rest, is what wins. If that's you, apply even if you don't tick every box. /pulliSDK, API, or developer-platform design with real attention to DX /liliRendering performance and Core Web Vitals /liliDesign systems and component architecture /liliStreaming or real-time interfaces /liliEdge delivery and distributed frontends /liliDocumentation, examples, and integration tooling /li /ulbBonus points /bulliExperience as an early engineer at a startup or fast-growing company /liliOpen-source components, libraries, or SDKs /liliAI-driven or generative UI work /li /ulbWhat we offer /bpWe'll ask a lot of you, and we give a lot in return. We want Callimacus to be a place where talented, driven people flourish, and we take that commitment seriously. A few things you'll find (and there's more): /pullibA product that will light you up. /bYou'll work at the frontier of what AI can do today, on problems nobody has solved before — which means most weeks you'll be reasoning from first principles rather than looking up how it's done. What you land becomes the way it works. /lilibAn exceptional opportunity for growth. /bYou'll work directly with the founders in a small, senior, talent-dense team, with high agency from day one, and play an essential role in the growth of the company. /lilibTop-of-the-Italian-market salary and equity. /bYou'll own a real piece of what you're building, aligning your growth with the company's long-term success. /lilibAmazing offices in the centre of Milan. /bIn the Moscova neighbourhood, one of the liveliest areas in the city and twenty minutes from anywhere. /lilibTop-of-the-market health insurance. /bComprehensive cover, for you and the people who depend on you. /lilibA welfare budget you decide how to spend. /bGym, mental health, museums, courses, travel — whatever actually makes your life better. /lilibGenuinely good food all day. /bHigh-quality, restaurant-level meals, including breakfast, lunch, and all-day snacks. /li /ulbOne note before applying /bpWe believe working side by side leads to faster progress, stronger ramp-up, and a culture built around community. For the next year we have decided to be in-person first. We've invested in making our workplace worth coming to, and we're happy to support your commuting. And we don't work by tickets: priorities get redefined often, sometimes mid-week, and you'll need to be comfortable with that. If you're set on remote or on a settled roadmap, this isn't your role. If you want to be in the room while the platform takes shape, we'd like to meet you. /ppbr/ppbLocation: /bOn-site, central Milan (Moscova area) /ppbStack: /bTypeScript, React, Node.js, AWS /ppbExperience: /b4–6 years (Mid) or 6+ years (Senior) /ppbGross annual salary: /b€45–55k (Mid) / €55–65k (Senior), plus equity /ppbr/p