Senior Design Engineer

About SummationSummation is building an AI Business Planning Platform for CFOs and finance teams. We combine a real-time modeling layer with Addison, our AI calculation engine, to turn messy enterprise data into decision-grade insights. Customers use Summation to model scenarios, explain variances, and automate weekly and monthly reviews.The RoleDesign Engineering at Summation lives at the intersection of product design and frontend engineering. As a Senior Design Engineer, you will ship beautiful, high-performance product experiences in production code, lead our design system, prototype new interactions, and raise the bar on accessibility, motion, and polish. You will partner closely with Product, Design, and Engineering, moving from Figma to code to shipped features.Roles & ResponsibilitiesBuild production UI in React and TypeScript for Summation’s web appLead the Summation Design System: tokens, components, theming, accessibility, docs, and release workflowPrototype end-to-end product ideas in code, validate with real data, and graduate winners into productionCraft motion and micro-interactions that clarify meaning and reduce cognitive loadTranslate flows and states from Figma into resilient, testable components with strong state managementDrive UI performance: bundle hygiene, code-split plans, rendering strategy, perceived latencyPartner with data visualization to express complex financial concepts with clarityEstablish guardrails: lint rules, Storybook checks, accessibility checks, visual regression in CIMentor engineers and designers on interaction patterns, system thinking, and front-of-frontend craftContribute to product quality across the stack through reviews, pairing, and high-signal documentationYou will love this role if youLove working across design and code, and care about the details users feelThink in systems: tokens, states, variants, docs, upgrade pathsPrototype ideas fast and are comfortable deleting code after an experimentBelieve accessibility, performance, and clarity are product featuresEnjoy collaborating with PMs, designers, and backend engineers in a high-context startupRequired experience4+ years building production web UI with React and TypeScriptStrong CSS fundamentals: layout, fluid type and spacing, responsive systems, motionDesign system experience: tokens, component architecture, Storybook, documentationData visualization in production using one of Recharts, D3, Visx, ECharts, or similarAccessibility and quality: semantic HTML, WCAG basics, keyboard and screen reader support, automated checksFigma fluency: components, variants, auto-layout, dev mode, and handoffProven ability to take a concept from Figma to shipped code without heavy PM overheadNice to haveRemix or Next.js, Tailwind, shadcn/uiFramer Motion for interaction designWebGL or Canvas experience for advanced interactionsVisual regression and accessibility tooling in CIExperience in fintech, analytics, or complex data products

• 4+ years building production web UI with React and TypeScript
• Strong CSS fundamentals: layout, fluid type and spacing, responsive systems, motion
• Design system experience: tokens, component architecture, Storybook, documentation
• Data visualization in production using one of Recharts, D3, Visx, ECharts, or similar
• Accessibility and quality: semantic HTML, WCAG basics, keyboard and screen reader support, automated checks
• Figma fluency: components, variants, auto-layout, dev mode, and handoff
• Proven ability to take a concept from Figma to shipped code without heavy PM overhead

Nice to have

• Remix or Next.js, Tailwind, shadcn/ui
• Framer Motion for interaction design
• WebGL or Canvas experience for advanced interactions
• Visual regression and accessibility tooling in CI
• Experience in fintech, analytics, or complex data products

• Build production UI in React and TypeScript for Summation’s web app
• Lead the Summation Design System: tokens, components, theming, accessibility, docs, and release workflow
• Prototype end-to-end product ideas in code, validate with real data, and graduate winners into production
• Craft motion and micro-interactions that clarify meaning and reduce cognitive load
• Translate flows and states from Figma into resilient, testable components with strong state management
• Drive UI performance: bundle hygiene, code-split plans, rendering strategy, perceived latency
• Partner with data visualization to express complex financial concepts with clarity
• Establish guardrails: lint rules, Storybook checks, accessibility checks, visual regression in CI
• Mentor engineers and designers on interaction patterns, system thinking, and front-of-frontend craft
• Contribute to product quality across the stack through reviews, pairing, and high-signal documentation

You will love this role if you

• Love working across design and code, and care about the details users feel
• Think in systems: tokens, states, variants, docs, upgrade paths
• Prototype ideas fast and are comfortable deleting code after an experiment
• Believe accessibility, performance, and clarity are product features
• Enjoy collaborating with PMs, designers, and backend engineers in a high-context startup