Robert Penner
Principal UX Engineer at Microsoft
New York, New York, United States
Summary
🤩
Rockstar🎓
Top SchoolRobert Penner is a Principal UX Engineer with over two decades of cross-disciplinary experience building award-winning front-end systems, design systems, and interactive visualizations for companies from startups to Microsoft and Adobe. Known for inventing the ubiquitous "Penner easing functions" and contributing to high-profile projects like the TIME-featured MTA Live Subway Map and Microsoft Fluent UI's motion system, he blends deep animation/math expertise with pragmatic engineering. He’s an inventor on multiple patents, a published author, and a prolific open-source maintainer whose libraries have been referenced by millions of files. Equally at home prototyping R&D and shipping production TypeScript/React components, he champions practices like mob programming, statecharts, and test-driven workflows to raise team craft. Based in New York, he pairs a background in philosophy and graph theory with hands-on experience across data science, backend microservices, and UX engineering—often surfacing elegant mathematical solutions to product problems.
13 years of coding experience
18 years of employment as a software developer
Graph Theory course, Graph Theory course at The University of British ColumbiaBA Philosophy, BA Philosophy at Trinity Western UniversityApplied Information Technology Diploma Software Development, Applied Information Technology Diploma Software Development at Information Technology Institute
English, Thai, Nepali
Stackoverflow
6,268reputation
736kreached
30answers
0questions
javascript
top-1%
casting
top-1%
typescript
top-1%
Github Skills (17)
javascript10
react-components10
ui-components10
typescript10
react-component10
casting10
component-kit10
fluentd10
react10
typescript-types9
typescripts9
css8
momentjs6
rxjs6
git6
Programming languages (4)
Github contributions (5)
microsoft/fluentui
Mar 2023 - Apr 2025
Fluent UI web represents a collection of utilities, React components, and web components for building web applications.
Role in this project:
Front-end Developer
Front-end DeveloperContributions:75 reviews, 42 PRs, 11 pushes in 2 years
Contributions summary:Robert primarily focused on improving the motion and animation capabilities within the Fluent UI web component library. Their contributions included fixing bugs in easing curves, refactoring the motion system to simplify variant creation, and implementing new features such as collapse with horizontal orientation and a delayed collapse variant. Furthermore, the user migrated existing components like MessageBar to leverage the new motion components, indicating a shift towards a more robust and flexible animation system.
web-componentsreact-component-libraryreact-componentsmicrosoftui-components
robertpenner/as3-signals
Sep 2012 - Oct 2015
Signals is a new approach for AS3 events, inspired by C# events and signals/slots in Qt.
Contributions:7 commits, 5 pushes in 3 years 1 month
eventsapproachas3signalsslots
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