Senior UX Engineer (+ Equity) at StackOne

This is a job that Jill, our AI Recruiter, is recruiting for on behalf of one of our customers. She will pick the best candidates from Jack's network. The next step is to speak to Jack. Job Title Senior UX Engineer Salary Not Disclosed + Equity Company Description StackOne is a $24M Series B startup, backed by Google Ventures and Workday Ventures, building the universal integration layer for modern SaaS products and AI agents. Job Description As the first dedicated UX Engineer at StackOne, you will be the internal authority on product polish and performance. You’ll own the design system, architect micro-frontends, and bridge the gap between design and engineering. Your work will directly impact how enterprise B2B customers interact with high-scale integration infrastructure and AI agentic workflows. Location London, UK Why this role is remarkable Founding-level impact: You are the first dedicated UX hire, responsible for setting the visual language and engineering standards for the entire frontend ecosystem.Elite backing: Work for a high-growth Series B company backed by top-tier investors including Google Ventures (GV) and Workday Ventures.Scale and Innovation: Build the critical infrastructure powering integrations for global SaaS leaders like Drata, while defining how AI agents interact with user interfaces. What You Will Do Own the StackOne design system by building reusable primitives and maintaining component libraries that power the entire product suite.Optimize frontend performance by instrumenting Core Web Vitals, managing bundle sizes, and ensuring a median Time to Interactive under two seconds.Collaborate with founders and product teams to prototype new features and establish AI-driven rules that maintain high UI standards across the codebase. The ideal candidate Brings 4+ years of professional experience in React and TypeScript with a portfolio demonstrating exceptional visual craft and attention to detail.Demonstrates deep proficiency in modern CSS (Tailwind), design system architecture, and performance tuning tools like Lighthouse and bundle analysis.Possesses a founder's mindset with the ability to navigate Node.js backends and monorepo tooling like Nx or Turborepo to eliminate bottlenecks. Who are Jack & Jill? Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support. And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate. How does this work? Jack's an AI agent for job searching and career coaching. He works for you.Jill is the AI recruiter working for the company. She recruits from Jack's network.If it's a match and the company wants to meet you, they'll make the intro. In the meantime, if you'd like, Jack will send you excellent alternatives. We never post fake jobs This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network. Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description. We appreciate this can make them look a bit suspect, but there isn't much we can do about it. Give Jack a spin! You could land this role. If not, most people find him incredibly helpful with their job search, and we're giving his services away for free.