Founding Full-Stack Engineer in United Kingdom

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Founding Full-Stack Engineer based in United Kingdom. This is a high-ownership engineering role at an early-stage, pre-launch startup, working directly with the founder to build and launch the product from the ground up. You will take primary ownership of the product’s UI and UX while contributing across the full stack whenever the product requires it. The role combines hands-on SvelteKit development with TypeScript, Tailwind CSS, Node. js, Fastify, and PostgreSQL. You will have significant autonomy over technical decisions, implementation speed, and how you solve product and engineering challenges. The environment is fast-moving and execution-focused, with minimal bureaucracy and an expectation that engineers take problems through to completion. You will also own frontend performance, deployment workflows, production debugging, and the foundations needed to scale the product reliably. This opportunity is particularly suited to an entrepreneurial engineer who enjoys building from zero and seeing their work reach production quickly. Accountabilities: - Build and ship SvelteKit applications end to end, including routing, load functions, server-side rendering, form actions, and client-side state management. - Develop strongly typed, maintainable TypeScript components and application logic using advanced typing patterns such as generics and discriminated unions. - Create responsive, accessible interfaces with Tailwind CSS, including custom design systems, reusable components, and component variants. - Build and maintain backend services and REST or RPC endpoints using Fastify, including schema-based request validation, error handling, and authentication middleware. - Design and modify PostgreSQL schemas, create and revert migrations, and write raw SQL or use query builders such as Drizzle, Kysely, or Prisma for complex queries.

- Take ownership of frontend performance, including bundle size, hydration costs, loading waterfalls, and Core Web Vitals. - Set up and maintain CI/CD pipelines for Node. js and SvelteKit applications, covering builds, linting, type-checking, and deployments. - Debug production issues across the frontend and backend without relying on separate specialists to resolve cross-stack problems. - Work directly with the founder to shape product decisions, technical direction, priorities, and execution. - Help establish the technical foundations of a product from zero, including repositories, hosting, databases, authentication, deployment, and development workflows. - Move quickly from problem identification to production-ready implementation while maintaining strong engineering standards. Requirements: - 4+ years of professional frontend engineering experience, including at least 1–2 years of hands-on SvelteKit experience. - Deep experience with another modern reactive framework such as React or Vue can be considered when paired with demonstrated ability to ramp up quickly on Svelte. - Strong TypeScript expertise, including generics, discriminated unions, complex API response types, and consistent end-to-end type safety. - Practical experience with Fastify or deep experience with comparable Node. js frameworks such as Express, Hono, or NestJS, with the ability to quickly learn Fastify’s plugin and hook architecture. - Strong hands-on PostgreSQL experience, including schema design, indexing fundamentals, migrations, raw SQL, and query performance analysis using tools such as EXPLAIN. - Comfortable working with PostgreSQL through the command line, rather than relying exclusively on ORM interfaces. - Production experience with Tailwind CSS, including custom theme configuration, reusable component abstractions, responsive design, and avoiding unnecessary utility duplication.