Husk

Svelte for .NET. No Node.

I wanted to write Svelte components in an ASP.NET Core app without putting a second toolchain on every laptop and build server. Husk runs the Svelte compiler inside dotnet build, in an embedded V8, so it does exactly that. You save a component, dotnet watch reloads the page, and dotnet publish ships plain JavaScript and CSS.

Note

Husk is a preview. The latest release is 0.1.0-preview.10, and the API can still change.

Try it

You need the .NET 10 SDK. In a web project:

dotnet add package Extrode.Husk.Build --version 0.1.0-preview.10
dotnet add package Extrode.Husk.AspNetCore --version 0.1.0-preview.10

Put PrivateAssets="all" on the Extrode.Husk.Build reference (it is a build tool, not app code), then add one line to Program.cs:

builder.AddHusk();   // recompiles on save; does nothing outside Development

Write wwwroot/App.svelte, a main.ts that mounts it and an index.html with <script type="importmap" data-husk></script>, and run dotnet watch. The step-by-step guide has every file.

Husk's build runs inside Pare's; Extrode.Husk.Build brings Extrode.Pare.Build in, so there is nothing to add for it.

What you get

You do	What happens
dotnet build	.svelte files become ES modules, with source maps and one husk.css, under obj/
save a component under dotnet watch	it is recompiled in the running app and the page reloads
dotnet publish	the site ships compiled, hashed files and no sources
write bad Svelte	the build fails: App.svelte(4,3): error HUSK100: ..., like a C# error

TypeScript works in components (<script lang="ts">, handled by Svelte) and in .svelte.ts rune modules (Pare strips the types). The compiler output is checked byte for byte against Node running the same Svelte (5.57.3), so you get what Svelte gives you.

What it costs

• The build package is about 6 MB (compiler plus Svelte). It depends on Microsoft's V8 native packages for six platforms (77 MB, shared across Husk versions). Both are restored once per machine and none of it ships with your app.
• There is no bundler. The browser loads many small modules through an import map.
• Husk compiles components. It is not SvelteKit: no router, no server rendering yet.
• The build machine has to be Windows, macOS or glibc Linux, x64 or arm64. The app you publish runs anywhere.

Documentation

The docs site is at husk.extrode.com. The same pages are in docs/:

• Why Husk
• Your first app
• What the build produces
• Husk in plain words
• MSBuild reference and error codes

Building from source

dotnet build Husk.slnx
dotnet test --solution Husk.slnx
scripts/pack-local.sh                       # packs into tmp/feed
dotnet watch --project samples/svelte-app   # the sample app

Third-party licenses ship in the build package: NOTICE.

License

Husk is under the Islamic Software License, Permissive (ISL-P) 1.2, with the Output Exception (ISL-OE) 1.2, the same terms as Pare. The exception means you can ship what Husk generates inside your own app. These are source-available licenses with ethical restrictions, not OSI-approved open source. See LICENSE.md and NOTICE.md. Svelte, ClearScript and V8 keep their own MIT and BSD licenses.

Contributing

Read CONTRIBUTING.md. Security reports go through GitHub's private vulnerability reporting: see SECURITY.md.

The repository also holds its working notes (work/, docs/specs, docs/decisions), and AGENTS.md for coding agents.