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.

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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+.

npm create tern@latest

It asks where to put the project and whether to start bare or with a full app. A bare app is the minimal, blog or api template, optionally styled with Tern UI. The full app (saas) has accounts with passkeys and two-step sign-in, a dashboard, settings and per-user data in SQLite. Then it offers to create a git repository and install packages. Without npm, go run github.com/Unfield/Tern/cmd/tern@latest new does the same. Then:

cd my-app
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, examples/dashboard for a shadcn-svelte dashboard, examples/status for a self-hosted status page with live updates, background jobs and notifications, and examples/accounts for user accounts with passkeys.

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
v1.2	Markdown and content, realtime, jobs and migrations, OAuth/OIDC, email, storage, typed endpoints with OpenAPI, starter templates, experimental Go components	Done
v1.3	Live components (Go component logic on the server, typed markup with tern check, several processes through a broker), the MCP server, Tern UI	Done
v1.4	Form validation from Go struct tags, checked in the browser too; the complete Tern UI with charts, data tables and auth screens; tern ui add; npm create tern; an analytics example app	Done
v1.5	Native rendering: tern build compiles the server renderer to Go, 12× faster than QuickJS on a 100-row table and faster than SvelteKit on a Node cluster	Done
v1.6	Fully native rendering; user accounts with passkeys, email verification, password resets and signed-in devices; Tern's own texts translatable	Done
v1.7	Two-step sign-in, sign-in with GitHub, Google or OIDC into accounts, email changes and rate limits; a faster JSON encoder and smaller binaries; render benchmarks in CI	Done
v1.8	A full app to start from (tern new asks bare or full); native rendering phase 2: page data as Go values and Svelte's renderer and helpers in Go, 272 µs for the 100-row table	Done

Documentation

• Guide: everything you need to build an app
• User accounts: sign-up, sign-in with passwords and passkeys, email verification, password resets, devices
• Live components: component logic in Go, on the server
• MCP server: tern mcp for AI coding tools
• Tern UI: accessible components with Tern's own design
• Coming from SvelteKit: what maps to what
• 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.