Storybook
Storybook is an open source tool that allows developers to build UI components in isolation, with interactivity, documentation and tests.
This is great for developing in teams, for sharing progress with designers, QA and developers alike. It is helpful in an organisation when onboarding new developers, and aiding designer-developer workflows
Storybook is framework agnostic, supporting React, Vue, Angular, Svelte, and more.