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Svelte: Write less code, ship faster UIs

Svelte takes a different approach to building UIs — instead of running in the browser, it compiles your code into tiny, framework-free JavaScript at build time.

Overview

Svelte is a compiler-based UI framework that eliminates the virtual DOM overhead of React and Vue. Your component code gets compiled into lean, optimized JavaScript before it ever runs in a browser. The result is apps that start faster, use less memory, and have smaller file sizes. Svelte's syntax is also notably concise — you write about 40% less code than equivalent React.

Core concepts

Single-file components: Script, styles, and HTML live in one .svelte file — no separate CSS files or JavaScript modules needed. Reactive assignments: Reassigning a variable (`count = count + 1`) automatically triggers a re-render. No setState calls. Reactive declarations ($:): Mark derived values with $: and Svelte updates them whenever their dependencies change. Compiler-based: Svelte ships zero framework code — your app is compiled to vanilla JS, making bundles tiny.

When to use Svelte

Performance is critical and bundle size matters You want a simpler, less verbose syntax than React Building interactive visualizations or animations

Quick-start tip

In Svelte, just declare a variable with `let count = 0` and use it directly in your template with `{count}`. No useState, no boilerplate — it just works.