threeui reached 3,771 stars in four days by open-sourcing the free tier of a paid product.

Created August 21 under MIT, it's the login-free Community edition of threeui.com: 50 parent components, 111 routes, 141 free variant records plus 23 singletons, shipping the full app shell, live renderers, controls and variant picker with only Pro and Beta catalog entries removed (GitHub). It publishes a React package to npm and the build runs a publication-boundary check to enforce the split. Worth studying if you're deciding how to open-source part of a commercial product without maintaining two codebases.