Svelte is a framework for building user interfaces on the web. It uses a compiler to turn declarative components written in HTML, CSS and JavaScript...

<script>
	function greet() {
		alert('Welcome to Svelte!');
	}
</script>

<button onclick={greet}>click me</button>

<style>
	button {
		font-size: 2em;
	}
</style>

<script lang="ts">
	function greet() {
		alert('Welcome to Svelte!');
	}
</script>

<button onclick={greet}>click me</button>

<style>
	button {
		font-size: 2em;
	}
</style>

...into lean, tightly optimized JavaScript.

You can use it to build anything on the web, from standalone components to ambitious full stack apps (using Svelte’s companion application framework, SvelteKit) and everything in between.

These pages serve as reference documentation. If you’re new to Svelte, we recommend starting with the interactive tutorial and coming back here when you have questions.

You can also try Svelte online in the playground or, if you need a more fully-featured environment, on StackBlitz.