Svelte is a free and open-source front end component framework or language created by Rich Harris and maintained by the Svelte core team members. Svelte is not a monolithic JavaScript library imported by applications: instead, Svelte compiles HTML templates to specialized code that manipulates the DOM directly, which may reduce the size of transferred files and give better client performance. Application code is also processed by the compiler, inserting calls to automatically recompute data and re-render UI elements when the data they depend on is modified. This also avoids the overhead associated with runtime intermediate representations, such as virtual DOM, unlike traditional frameworks (such as React and Vue) which carry out the bulk of their work at runtime, i.e. in the browser.

The compiler itself is written in TypeScript. Its source code is licensed under MIT License and hosted on GitHub.

Svelte is a radical new approach to building user interfaces. Whereas traditional frameworks like React and Vue do the bulk of their work in the browser, Svelte shifts that work into a compile step that happens when you build your app. Instead of using techniques like virtual DOM diffing, Svelte writes code that surgically updates the DOM when the state of your app changes.

We're proud that Svelte was recently voted the most loved web framework with the most satisfied developers in a pair of industry surveys. We think you'll love it too. Read the introductory blog post to learn more.

The predecessor of Svelte is Ractive.js, which Rich Harris had developed earlier.

• Version 1 of Svelte was written in JavaScript and was released on 29 November 2016. It was basically Ractive with a compiler. The name Svelte was chosen by Rich Harris and his coworkers at The Guardian.
• Version 2 of Svelte was released on 19 April 2018. It set out to correct what the maintainers viewed as mistakes in the earlier version such as replacing double curly braces with single curly braces.
• Version 3 of Svelte is written in TypeScript and was released on 21 April 2019. It rethought reactivity by using the compiler to instrument assignments behind the scenes.

The SvelteKit web framework was announced in October 2020 and entered beta in March 2021. Key early contributors became involved with Conduitry joining with the release of Svelte 1, Tan Li Hau joining in 2019, and Ben McCann joining in 2020. Rich Harris and Simon Holthausen joined Vercel to work on Svelte fulltime in 2022. SvelteKit 1.0 was released in December 2022 after two years in development

Svelte is widely praised by developers. Taking the top ranking in multiple large scale developer surveys, it was chosen as the Stack Overflow 2021 most loved web framework and 2020 State of JS frontend framework with the most satisfied developers. A community group of non-maintainers run the Svelte Summit conference, write a Svelte newsletter, host a Svelte podcast, and host a directory of Svelte tooling, components, and templates