Storybook

Storybook is the workshop where you build your UI components on the side, isolated from the rest of the app. Instead of navigating through your product to reach a specific state of a button or modal, you write "stories" that show each component in all its variants. The result: you see, document, and test your UI without depending on app context. It works with React, Vue, Angular, Svelte, and most frameworks, and it's free and open source.

For a team maintaining a design system, it's nearly essential: the component library becomes a living source of truth shared between devs and designers. Paired with Chromatic (the paid cloud service from the same authors), you get automatic visual regression testing.

The trade-off is the upfront investment. Setting up Storybook and writing stories takes time, and on a small solo project the overhead often isn't worth it. The real question isn't "is it good" (it is), but "does my project have enough shared components to justify it". For a team design system, the answer is almost always yes.