Storybook 10 debuts ESM-only, 29% lighter, module automocking, and typesafe CSF Factories
Storybook 10 arrives as a major update for UI designers and frontend developers, focusing on performance and modern workflows. The switch to ECMAScript Module (ESM)-only support marks the main breaking change. This overhaul reduces install size by another 29 percent, following significant savings in version 9.
Alongside these improvements, Storybook’s collaboration with Vitest introduces a next-generation module mocking solution. The new system works in both development and static production builds, and is compatible with Vite and Webpack, making it more accessible to teams modernizing their tooling.
Within the component authoring experience, the Component Story Format (CSF) gets a significant upgrade. CSF Factories, now promoted from Experimental to Preview, deliver better type safety and improved autocompletion, alongside enhanced ergonomics for story writers.
Workflow improvements continue with easier story editing and sharing, plus expanded capabilities for tags. Storybook now lets users exclude stories by selected tags and configure default UI states directly in configuration files.
For framework support, Storybook 10 adds Svelte async component support and mock state, closing a key gap for SvelteKit users. Following these platform broadening changes, this release also ensures compatibility with Next.js 16 and Vitest 4.
