Raven

Brings a comprehensive design knowledge base into Claude's context when you're building UI. You get queryable access to Nielsen heuristics, Laws of UX, WCAG rules, proven patterns for signup flows and dashboards, voice and tone systems from Mailchimp and GOV.UK, plus design tokens from Stripe and Linear. The audit tools are the real hook: paste SwiftUI code to catch hardcoded fonts and undersized touch targets against Apple HIG, or feed it an iOS accessibility snapshot to score contrast and spacing in points. Also includes research method checklists, service blueprinting with HTML output, and metrics frameworks like HEART and AARRR. Useful when you want Claude to generate UI that follows actual design systems instead of guessing.