Interim Senior Frontend Engineer

Go Fractional; Berlin; Hybrid; EUR 85,000 - 110,000; Full time

Job summary

Go Fractional is seeking a best-in-class frontend engineer to own the web platform end to end. You will lead architecture decisions, ensure high quality code, and deliver data-heavy UI that supports invoices and tenant management.

You will mentor juniors while collaborating closely with backend engineers and founders. The role focuses on a SvelteKit + TypeScript stack, with Tailwind/DaisyUI for a consistent UI, and requires strong TypeScript, testing practices, and an ability to ship features

Qualifications

• 5+ years of professional frontend experience.
• 2+ years building production apps with Svelte and SvelteKit.
• Strong TypeScript: strict mode and generics.
• Hands-on with Tailwind CSS (DaisyUI a plus).
• Experience with RPC-style APIs and typed contracts between frontend and backend.
• Testing as a habit: Vitest.
• Comfortable in a Unix environment with Git and PRs.
• Fluent English, written and spoken.
• Based in Berlin or willing to move; office 2–3 days a week.

Responsibilities

• Own the frontend architecture of the SvelteKit app: routing, load functions, SSR, state management and backend communication.
• Ship features end to end from concept to production, sometimes before final design.
• Develop data-heavy UI: dashboards, billing documents, tenant/owner management.
• Maintain the component library with Tailwind/DaisyUI for consistency.
• Raise the bar on code quality: TypeScript discipline, test coverage, code reviews.
• Collaborate with backend on API contracts (types, schemas, error handling).
• Mentor juniors through reviews and pairing.

Skills

Frontend development

Svelte/SvelteKit

TypeScript

Code quality

Mentoring

English fluency

Team collaboration

React avoidance/decision making

Unix/Linux

Git workflows

Tools

SvelteKit

Tailwind CSS

DaisyUI

oRPC/tRPC

Vitest

Job description

Contract details

• Fixed-term contract (Befristeter Arbeitsvertrag)
• 12-month contract
• 6-month probation period
• 40 hours/week
• 24 days of annual leave
• As soon as possible

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.