Builds consistent React apps for developers and AI agents
Once UI is an open-source design system for building polished React products with less repetitive code. Compose layouts with readable primitives, use a shared system of components and design tokens, and keep the result consistent as your product grows. Version 2.0 gives both you and your coding agent a clearer way to work. Its component catalog, compact rules, and task guides help agents use the system correctly; its foundations and predictable APIs make the output easier for you to understand.
Once UI 2.0 launched on Product Hunt on 2026-09-25 and has 73 upvotes and 1 comments so far.
This tool is open source.