Senior UI Systems Engineer - AI SaaS
1 day ago
City of London
Shape the design system behind a unicorn AI-native SaaS platform, scaling globally at speed. Why This Role? Stax is partnering with a unicorn AI-native SaaS scale-up that’s transforming how organisations use AI. Now they’re building a London engineering hub. Join as a UK founding engineer - hybrid working, high impact, and the chance to shape a category-defining platform from day one. The Opportunity This is a systems-level role at the intersection of design and engineering. You’ll be at the heart of a platform that’s changing how organisations use AI for customer support and product operations. In just four years, the team has: • Pushed browser limits with D3-powered visualisations and real-time dashboards, • Open-sourced client-side analytics on DuckDB, bringing OLAP to the edge, • Built AI-native UIs that feel fast, intelligent, and fun, • Scaled a themeable design system adopted across multiple products and platforms, • Introduced micro-frontends that power independent, high-velocity teams—and let customers embed their own modules directly in the product What You’ll Do • Evolve the design system: tokens, theming, accessibility, visual language, • Build React + Web Component libraries for core + embedded apps, • Advance tooling: Storybook, Chromatic, Figma plugins, • Set standards and governance across design + engineering, • Deliver performant layouts and visualisations at scale, • Mentor peers on accessibility and performance-first development Tech Ecosystem You’ll Shape Design Tokens · Figma API · Storybook · React · Web Components · TypeScript · Tailwind CSS · Vite · NextJS · Jest · Cypress · Playwright What You Bring • 8+ years in large-scale web apps, 2+ in design-system architecture, • Strong perspective on tokens, theming, multi-brand support, • Mastery of React + TypeScript, with library publishing experience, • Accessibility leadership (WCAG, ARIA, keyboard nav, colour contrast), • Fluency in CSS methodologies and testing frameworks, • Excellent communication skills to align design, product, and engineering, • Bonus points for OSS contributions, Figma plugins, or micro-frontend orchestration Culture & Impact • Speed with craftsmanship: fast feedback, continuous delivery, peer reviews, • Performance-first mindset: Core Web Vitals as product metrics, • Inclusive and global: teams across the US, Europe, and India, • Autonomy with accountability: design, guide, measure, iterate, • London hub: hybrid model, build the team and culture from the ground up Why join? Your design system will power products used by some of the world’s most ambitious teams. Join at a moment of hyper-growth and play a defining role in one of the most exciting SaaS platforms in the world. Stax welcomes applications from all backgrounds. Our client unfortunately can't offer visa sponsorship.