| 1 | [](https://github.com/snowpackjs/snowpack/actions)
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| 3 | ### What is Snowpack?
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| 5 | **Snowpack is a modern, lightweight toolchain for web application development.** Traditional dev bundlers like webpack or Parcel need to rebuild & rebundle entire chunks of your application every time you save a single file. This introduces lag between changing a file and seeing those changes reflected in the browser, sometimes as slow as several seconds.
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| 7 | Snowpack solves this problem by serving your application **unbundled in development.** Any time you change a file, Snowpack never rebuilds more than a single file. There's no bundling to speak of, just a few milliseconds of single-file rebuilding and then an instant update in the browser via HMR. We call this new approach **O(1) Build Tooling.** You can read more about it in our [Snowpack 2.0 Release Post.](https://www.snowpack.dev/posts/2020-05-26-snowpack-2-0-release/)
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| 9 | When you're ready to deploy your web application to users, you can add back a traditional bundler like Webpack or Parcel. With Snowpack you get bundled & optimized production performance without sacrificing dev speed by adding an unnecessary bundler,
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| 11 | ### Key Features
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| 13 | - A dev environment that starts up in **50ms or less.**
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| 14 | - Changes are reflected [instantly in the browser.](https://www.snowpack.dev/posts/2020-05-26-snowpack-2-0-release/#hot-module-replacement)
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| 15 | - Integrates your favorite bundler for [production-optimized builds.](https://www.snowpack.dev/posts/2020-05-26-snowpack-2-0-release/#snowpack-build)
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| 16 | - Out-of-the-box support for [TypeScript, JSX, CSS Modules and more.](https://www.snowpack.dev/posts/2020-05-26-snowpack-2-0-release/#features)
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| 17 | - Connect your favorite tools with custom [build scripts](https://www.snowpack.dev/posts/2020-05-26-snowpack-2-0-release/#build-scripts) & [third-party plugins.](https://www.snowpack.dev/posts/2020-05-26-snowpack-2-0-release/#build-plugins)
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| 19 | **💁 More info at the official [Snowpack website ➞](https://snowpack.dev)**
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