Core Technologies / React

React 19
UI Engineering

The industry standard for building dynamic, component-driven user interfaces.

Concurrent React

React 19 makes concurrent rendering stable. UI updates can be interrupted, ensuring your app stays responsive even during heavy rendering tasks.

  • useTransition for non-blocking updates
  • useDeferredValue for debouncing
  • Automatic batching
  • Suspense for data fetching
SCHEDULER: READY
60.0 FPS
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Scheduler Trace

Ready. Click 'Simulate User Input' to test.

Interrupts: 0

Concurrent rendering allows React to interrupt in-progress low-priority renders to process high-priority user interactions instantly, ensuring high responsiveness.

Server Components

Execute components on the server ahead of time. This reduces bundle size and allows direct, secure access to backend resources.

  • Zero bundle size impact
  • Direct database access
  • Seamless integration with client components
  • Improved initial page load
RSC Data Flow Visualizer
SERVER
Server EnvironmentSecure Direct DB Query
const users = await db.query()
READY
CLIENT
Client Webpage0 KB JS Bundle
Pure HTML Rendered

React Server Components execute components exclusively on the server, permitting secure DB query integrations while eliminating DOM client bundle overheads.

Actions API

React 19 introduces native Actions, enabling you to manage form submissions, pending states, and optimistic UI updates cleanly without boilerplate.

  • Native useActionState hook
  • Built-in pending state management
  • Optimistic UI updates with useOptimistic
  • Simplified form handling
Actions Pending & Optimistic API
Form Idle
Server User Registry
AliceBob
Optimistic Updates Status
✓ All changes synced

React 19 native Actions handle pending states, optimistic updates, and form submissions automatically, eliminating boilerplate code.

The 'use' Hook

The new use() API is a game-changer. It allows you to unwrap Promises and read Context dynamically, even inside loops or conditionals.

  • Read Promises during render
  • Seamless Suspense integration
  • Dynamic Context reading
  • Cleaner asynchronous components
Suspenseful use() API Promise
// Client Component with use()
function FeedItem({ promise }) {
const data = use(promise);
return <div>{data}</div>;
}
Conduit idle. Click trigger.

The new use() API lets you read the value of a Promise or Context right inside your render function. It works seamlessly with Suspense.

Built-in Metadata

Forget third-party helmet libraries. React 19 natively supports rendering <title>, <meta>, and <link> tags anywhere in the tree, hoisting them to the document head automatically.

  • Native document head management
  • Automatic tag hoisting
  • SEO friendly metadata
  • No extra dependencies required
Hoisting Editor
function MainLayout() {
return (
<title></title>
<meta name="author" content="Jane" />
<p>Dynamic App Context</p>
)
}
React 19 Engineering
Hydrated HEAD tags✓ Document title hoisted to browser head!

React 19 hoists document metadata. You can safely render title, meta, and link tags from any component without third-party libraries.

Modern UI

Build with React.

Deliver highly interactive, blazing fast user interfaces.