Owen Williams is a design manager at Stripe who built Protodash, an internal AI-powered prototyping platform that lets designers and PMs create high-quality Stripe dashboard prototypes without writing code. What started as a bundle of Cursor rules and React components evolved into a full web-based prototyping studio that runs in dev boxes, complete with design review modes, variant testing, and AI-powered iteration. Surprisingly, PMs now use Protodash just as much as designers, fundamentally changing how Stripe approaches prototyping, design reviews, and engineering handoffs.

What you’ll learn:

How Stripe built an internal AI prototyping tool using Cursor rules, MCPs, and their design system
Why “blurple slop” happens when designers use generic AI tools—and how to fix it
The architecture behind Protodash: React router, design system components, and MCP integrations
How Stripe prototypes in dev boxes so designers never have to worry about local setup
Why “demos, not memos” transformed Stripe’s design review culture
How Stripe built design review modes, variant testing, and AI annotation directly into your prototyping tool
Why internal tools don’t need to be production-grade to be transformative

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Brought to you by:

Celigo—Intelligent automation built for AI

Cursor—The best way to code with AI

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In this episode, we cover:

(00:00) Welcome and intro to Owen Williams

(02:19) The “blurple slop” problem with AI design tools

(03:50) Protodash: an internal vibe-coding tool for Stripe prototypes

(05:26) Why an engineering background helped Owen lower the bar for designers

(07:55) The Cursor rules that taught the Stripe design system

(09:04) Running prototypes on dev boxes vs. locally

The internal AI tool that’s transforming how Stripe designs products | Owen Williams