Tern

README

Tern

Svelte on the client. Go on the server.
A full-stack web framework with file-based routing, typed data loading and single-binary deploys.

[!NOTE] Tern 1.0 is stable: minor releases do not break the public API. See the stability promise.

---

Why Tern?

SvelteKit has one of the best developer experiences on the web, but its server code runs on Node. Tern keeps the parts that make SvelteKit pleasant, such as file-based routes, load functions, form actions and layouts, and runs everything server-side in Go.

• Real Svelte 5. Not a lookalike. Your components, the Svelte ecosystem and your editor tooling all keep working.
• Go on the server. load functions and form actions are plain Go, built on net/http.
• End-to-end types. The structs your Go Load returns become TypeScript types for your Svelte pages, generated automatically.
• Server-side rendering. Pages render in Go through an embedded JavaScript engine and hydrate in the browser. No Node in production.
• One binary. tern build embeds the client and the renderer into a single static Go executable.
• Progressive enhancement. Forms work without JavaScript, and get better with it.

Getting started

You need Go 1.26+ and Node.js 22+.

go run github.com/Unfield/Tern/cmd/tern@latest new my-app
cd my-app
npm install
npm run dev

Open http://localhost:5173. npm run build produces build/my-app, a single binary that serves the whole app.

A taste

src/routes/
├── +layout.svelte
├── +page.svelte
└── blog/slug.param/        # → /blog/[slug]
    ├── page.server.go
    └── +page.svelte

// src/routes/blog/slug.param/page.server.go
package page

import "github.com/Unfield/Tern/kit"

type Data struct {
	Title string `json:"title"`
	Body  string `json:"body"`
}

func Load(ctx *kit.Ctx) (Data, error) {
	post, err := posts.Find(ctx.Param("slug"))
	if err != nil {
		return Data{}, kit.NotFound()
	}
	return Data{Title: post.Title, Body: post.Body}, nil
}

<!-- src/routes/blog/slug.param/+page.svelte -->
<script lang="ts">
  import type { PageProps } from './$types';
  let { data }: PageProps = $props(); // fully typed from the Go struct
</script>

<h1>{data.title}</h1>
<article>{data.body}</article>

Dynamic directories use Go-safe names, because Go import paths cannot contain brackets: slug.param for [slug], lang.optional for [[lang]], path.rest for [...path], and app.group for (app). See examples/todos for a complete app with sessions, form actions, a protected route group and an API endpoint.

Status

Milestone	Scope	State
v0.1	Router, loads, actions, endpoints, typegen, dev server, single-binary build	Done
v0.2	Server-side rendering and hydration	Done
v0.3	Prerendering, streaming, deployment guides	Done
v0.4	Typed links, navigation hooks, selective reloading, CSP, a shadcn-svelte dashboard example, docs site	Done
v1.0	Plugins, base paths, public environment variables, the stability promise	Done
v1.1	Translations, responsive images, service workers, sessions, metrics, rate limiting and CORS plugins	Done

Documentation

• Guide: everything you need to build an app
• Architecture: how Tern works internally
• Deployment: running Tern in production
• Benchmarks: how fast the pieces are
• Stability: what the version numbers promise
• Roadmap: what is planned, and in what order
• Decision records: why things are the way they are

Contributing

Contributions are welcome. Please read CONTRIBUTING.md and our Code of Conduct first. To report a security issue, follow SECURITY.md.

License

MIT © The Tern Authors

Tern is an independent project and is not affiliated with or endorsed by the Svelte team.