Product engineer for Spend Management.
- Rebuilt a legacy form library with TypeScript and React hooks, using advanced types to preserve backwards compatibility.
Frontend engineer · Product-minded, systems-oriented
William Lubelski
Frontend Engineering
San Mateo, California[email protected]I build thoughtful products and the systems that make them easier to develop, maintain, and evolve.
Explore the workFIG. 01 / ENGINEERING PRACTICEWL–001
TO THE UNDERLYING SYSTEM.[ NOT TO SCALE ]
- Current / Mercury
- Senior Frontend Engineer
- Product area
- Spend Management
- Core tools
- TypeScript / React / CSS
01 / Experience
Products built.
Systems improved.
- Led a team to improve Shift Management search performance, reducing page load times for larger customers from multiple minutes to 500 ms.
- Led the navigation and branding overhaul for the Payroll product.
- Built frontend infrastructure for localization, wizard workflows, type-safe reactive localStorage, and client-side navigation alongside legacy server-rendered pages.
- Re-architected data fetching and the frontend of TotalComp.
- Designed and built the frontend for the HRIS integration system.
- Supported a junior engineer leading the Total Rewards frontend project; advocated for and adopted Carta’s micro-frontend system.
- Built the customer-facing payments and account management portal.
- Designed a system to embed the customer portal in the admin portal for smoother support interactions.
- Led the transition from a white-label CMS prototype to an in-house web application, prioritizing simple, maintainable architecture.
- Mentored junior engineers through pair programming and cross-team collaboration.
- Built features for data-rich CRM and nonprofit fundraising applications using React and Backbone.
- Designed and built a Flux-based state management library, then helped transition the application to modern React practices.
- Mentored junior frontend developers.
Earlier experience includes frontend development at Kitewheel (2014), UX at SoftArtisans (2011–2012), and mechanical engineering at Bicon Dental Implants (2008–2011, 2012–2014).
02 / Technical Practice
Behind the interface.
TypeScript & JavaScript
Type-safe APIs, recursive and mapped types, and backwards-compatible library design.
React & architecture
Hooks, state management, data fetching, performance, and legacy-system integration.
CSS & interface design
CSS-in-JS, styled-components, LESS, PostCSS, and vanilla CSS. A grounding in UX and human factors.
03 / Education
A systems-first
perspective.
University at Buffalo (SUNY)
B.S. Aerospace Engineering · B.A. Mathematics
Bentley University
Coursework in Human Factors in Information Design: user research, testing and assessment, and measuring user experience.
General Assembly
Product Management evening course · Boston, MA
04 / Contact