Senior Frontend Engineer

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About the role

About Heidi Systems Heidi Systems builds the energy OS for real estate. We help property managers and owners get their heating, water and electricity meters online, see consumption in real time and run the yearly utility billing without paper, Excel and site visits. Submetering in Germany is still mostly analog. Meters get read by hand, data sits in PDFs, and tenants see their consumption once a year. We change that end to end: we install the meters and gateways in the building, collect the data and build the web platform property managers work in. We're a small team in Berlin. Product and engineering work directly with the founders, and what you ship lands with real customers fast. The role We're looking for a best-in-class frontend engineer. Someone whose code other engineers learn from. You'll be our senior frontend engineer and own the web platform end to end: architecture, code quality and the day-to-day experience of the property managers using it. The platform is a SvelteKit and TypeScript app. It shows consumption data per building and unit, flags anomalies, manages tenants and owners, and produces the documents for the yearly billing. A lot of it is data-heavy UI, and it has to be right, because the numbers end up on invoices. You'll work closely with our backend engineers and the founders, and you'll help onboard and mentor junior developers and interns as the team grows. What you'll do • Own the frontend architecture of our SvelteKit app: routing, load functions, SSR, state and how we talk to the backend via oRPC • Ship features end to end, from a rough idea with the founders to production, often before the design is final • Build the data-heavy parts of the product: consumption dashboards, notification rules, tenant and owner management, billing documents • Set up and maintain our component library on Tailwind and DaisyUI so the UI stays consistent as we add features • Raise the bar on quality: strict TypeScript, Vitest coverage, code reviews, a sane PR flow • Shape the API contract together with backend (types, Zod schemas, error handling) so frontend and backend stay in sync • Mentor juniors and interns through reviews and pairing What you bring • 5+ years of professional frontend experience, ideally at startups or other fast-moving product teams • 2+ years building production apps with Svelte and SvelteKit, with a deep understanding of its reactivity model, stores, lifecycle, routing, load functions and SSR • Strong TypeScript: strict mode, generics, utility types, and the judgment to know when types help and when they get in the way • Hands-on with Tailwind CSS (DaisyUI is a plus) • Experience with RPC-style APIs (oRPC, tRPC or similar) and typed contracts between frontend and backend • Testing as a habit: Vitest, JSDom or comparable tooling • Comfortable in a Unix environment (Linux or macOS), with Git, branches and PRs • You've made architecture decisions on a real product and can explain the trade-offs • You work well with little oversight and ship in small, frequent steps • Fluent English, written and spoken • You're in Berlin or willing to move, and you're in our office 2 to 3 days a week How we work • Hybrid in Berlin. You're in the office 2 to 3 days a week. That's fixed. The rest of the week you work from wherever you like. • Short paths. You talk to the founders directly, most decisions take one call. • Real ownership. The frontend is yours to shape, and you'll set many of the standards the team builds on. • Real impact. Your work runs in buildings across Germany and makes energy use visible where people live. • Room to grow with the company as the engineering team gets bigger. Your next steps If you match most of these requirements and are ready to help digitize the building sect

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