Learn to build fast, reactive applications with signals-based state management, fine-grained DOM updates, and islands architecture.
Create your first What app and learn the core concepts in under 5 minutes.
Build a complete game step by step. Learn signals, components, and state management.
Understand fine-grained reactivity — the core mental model behind What Framework.
Ten copy-paste patterns for how agents should write, debug, and maintain What code.
The 29-tool MCP server that lets an agent inspect a running app in real time.
A machine-readable index of this site for LLMs. See also llms-full.txt.
Build reusable UI pieces with props, children, and composition patterns.
Run side effects in response to signal changes. Cleanup and dependencies.
<Show>, <For>, <Switch> — cleaner conditional and list rendering.
useSWR, useQuery, useInfiniteQuery — fetch, cache, and sync server state with built-in primitives.
Build validated forms with useForm, useField, and built-in validation rules. Zod and Yup support.
Global state management with reactive stores. Define state, computed values, and actions in one place.
Client-side navigation with dynamic params, nested layouts, middleware, and view transitions.
SWR caching, query deduplication, cache invalidation, and offline-first data strategies.
Ship zero JS by default. Hydrate interactive components on idle, visible, or interaction.
SSR with streaming, server actions, optimistic updates, and CSRF protection.
Physics-based springs, tweens, transitions, and gesture detection built in.
Focus management, ARIA helpers, screen reader announcements, and keyboard navigation.
onMount, onCleanup, and component lifecycle patterns.
Share state across your component tree without prop drilling.