Frontend Engineer - UI/UX

Our client is an exciting AI Start up company and they have an immediate need for a Frontend Engineer. This position will own the decision surface enterprise that senior leaders will act on every day. You will own that experience end to end: the widget and data-visualization system, the design system, and the onboarding and polish that make enterprise users want to live in the product every day. Responsibilities Own and evolve the decision surface: the SSR routes, the auth and session flow, and the overall front-end architecture.Build out the widget and data-visualization system: chart types, per-source breakdowns, color palettes, and an add-widget builder, driven by the front-end state layer.Shape the insights deck and Kanban: the surfaces where operators triage AI-detected insights, drag them across columns, assign owners, and work action-step and comment threads.Wire the front end to the backend data API, tuning the metric catalog, theming, and export layers.Define and grow a coherent design system: components, tokens, motion, and empty, loading, and error states, so new surfaces ship fast and feel consistent.Build onboarding and connection flows (OAuth-backed source connections, first-run experiences) that get a new enterprise tenant to first insight quickly.Partner directly with the Head of Engineering on product and UX decisions, and help define what polished means.Keep the front end honest with the multi-tenant model: every view is tenant-scoped and never leaks across boundaries. Requirements Strong TypeScript and React experience and a genuine eye for UI and UX;2-4 years of experience in Front End and UI/UXReal data-visualization sensibility; Experience building charts and dashboards and can reason about representing multi-source, time-series data clearly.Comfortable owning a front end end to end: component architecture, state management, performance, and accessibility.Experience integrating REST and JSON APIs and shaping and normalizing server data for the UI.Product instinct; you can take an ambiguous request to make a flow better and turn it into shipped, tested UI.Comfortable in a startup environment: high ownership, low ceremony, comfortable with early-stage ambiguity.Able to be in the Toronto office two days a week. Nice to Haves Experience with a modern SSR or islands framework and a utility-first CSS framework.Built or maintained a design system or component library.Familiarity with multi-tenant SaaS patterns (Postgres, row-level security).Exposure to the digital advertising or marketing-analytics domain.Comfort dipping into the Python backend when a feature needs it.