Svelte

Svelte is an open-source front-end framework for building web applications. Unlike traditional frameworks that run in the browser with a large runtime, Svelte compiles components into highly optimized JavaScript during build time, producing code that surgically updates the DOM. It was created by Rich Harris and first released in 2016, with a major rewrite culminating in the Svelte 3 compiler, which popularized the compiler-based approach used by the project.

Developers write components in .svelte files, which combine HTML-like markup, JavaScript, and CSS. At compile time, the Svelte compiler converts these components into imperative code that manipulates the DOM directly. Reactivity is built into the language: variable assignments update the UI, and reactive statements using the $: syntax re-run when dependencies change. The framework also provides stores, such as writable and derived, for sharing state across components, with a convenient $ prefix for auto-subscription.

For applications, Svelte offers SvelteKit as the official app framework, providing server-side rendering, routing, code splitting, and static site generation. Svelte's tooling typically uses Vite as a bundler, and the ecosystem includes support for TypeScript. There is also an ecosystem project called Svelte Native for mobile development with NativeScript, though it is separate from the browser-oriented core. Svelte is distributed under the MIT license.

Compared with other frameworks, Svelte tends to produce smaller bundle sizes and faster startup times due to its compile-time approach. It is suitable for small to medium-sized projects and for teams seeking a straightforward component model, though very large apps may still require deliberate tooling and patterns. The project is maintained by the Svelte core team and an active open-source community around GitHub.