Building With One

One Framework Guide

Official docs: Introduction, Installation, Configuration

One is a full-stack React framework targeting both web and React Native with a single codebase. Built on Vite with file system routing, server-side loaders, and flexible render modes (SSG, SSR, SPA). For native builds, One supports Metro (recommended) and an experimental Vite bundler.

References

Consult these resources as needed:

references/
  routing.md              File conventions, dynamic routes, groups, parallel routes, intercepting routes, typed routes
  layouts.md              _layout.tsx, Stack (+ Header Composition API), Tabs, Drawer, Slot, NativeTabs, nested layouts
  navigation.md           Link (mask, scroll, asChild), useRouter, useLinkTo, Protected, Redirect, route masking
  components.md           Head (+ iOS Handoff/Spotlight), SafeAreaView, ScrollBehavior, LoadProgressBar, withLayoutContext
  hooks.md                All hooks: useParams, useSearchParams, useActiveParams, useSegments, useMatches, useBlocker, etc.
  configuration.md        vite.config.ts, one() plugin options, web/native/global settings, env vars
  render-modes.md         SSG, SSR, SPA, API per-page and global, folder suffixes, layout render modes
  middleware.md           _middleware.ts, createMiddleware, auth, CORS, redirects, context sharing
  devtools.md             Alt+Space spotlight, SEO preview, route debug, loader timing, source inspector, input recording

Quick Start

npx one

This scaffolds a new project with starter templates. Then:

bun install
bun run dev

Access at http://localhost:8081. For native, use Expo Go or build with one prebuild and one run:ios.

Project Structure

app/
  _layout.tsx          Root layout (Stack, Tabs, Drawer, or Slot)
  _middleware.ts       Server middleware (optional)
  index.tsx            Home route (/)
  about.tsx            Static route (/about)
  blog/
    [slug].tsx         Dynamic route (/blog/:slug)
    _layout.tsx        Nested layout
  dashboard+spa/       SPA folder (all children are SPA)
    index.tsx
  api/
    route+api.ts       API endpoint (/api)
    users/[id]+api.ts  Dynamic API route
  +not-found.tsx       404 page
vite.config.ts         One configuration
app/routes.d.ts        Auto-generated route types

Key Rules

• Routes live in the app/ directory only
• Never co-locate components, types, or utilities in app/ — keep them in src/, components/, etc.
• Always have a route that matches / (even inside a group route)
• Use _layout.tsx for layouts — it must render <Slot>, <Stack>, <Tabs>, or <Drawer>
• Use +api.ts suffix for API routes, not regular route files
• Platform-specific files: .web.tsx, .native.tsx, .ios.tsx, .android.tsx — never import these directly, the bundler resolves them
• Pin the one version for production stability

CLI

one dev [--clean] [--host] [--port] [--debug]  # dev server (web + native)
one build [web | ios | android]                 # production build
one serve [--cluster] [--port]                  # production server (Hono)
one prebuild                                    # generate native Xcode/Android projects
one run:ios                                     # build and run iOS app
one run:android                                 # build and run Android app
one generate-routes [--typed=runtime|type]       # regenerate route types
one patch [--force]                             # apply package patches

Configuration

All config goes through the Vite plugin in vite.config.ts:

import { one } from 'one/vite'

export default {
  plugins: [
    one({
      web: {
        defaultRenderMode: 'ssg',
        deploy: 'node',          // 'node' | 'vercel' | 'cloudflare'
        linkPrefetch: 'intent',  // trajectory-based prefetching
        sitemap: true,
      },
      native: {
        bundler: 'metro',        // recommended for stability
      },
    }),
  ],
}

See ./references/configuration.md for all options.

Running the App

Web:

one dev

Native with Expo Go (recommended for quick iteration):

one dev
# press q, r in terminal to show QR code
# scan with Expo Go app

Native with custom build (for custom native dependencies):

one prebuild
one run:ios    # or one run:android

Production:

ONE_SERVER_URL=https://myapp.com one build
one serve --cluster  # cluster mode for high traffic

Code Style

• Use process.env.EXPO_OS instead of Platform.OS for platform checks
• Use import.meta.env.VITE_ENVIRONMENT for environment checks ('client', 'ssr', 'ios', 'android')
• Prefix client-exposed env vars with VITE_, EXPO_PUBLIC_, or ONE_PUBLIC_
• Add /// <reference types="one/env" /> to a .d.ts file for typed env vars
• Use createRoute<'/path/[param]'>() for fully typed route params and loaders

Routing Exports

Route files support special exports:

// loader — server-side data fetching (tree-shaken from client)
export async function loader({ params, path, request }) { ... }

// generateStaticParams — expand dynamic SSG routes at build time
export async function generateStaticParams() { return [{ slug: 'hello' }] }

// sitemap — control sitemap.xml entry for this route
export const sitemap = { priority: 0.8, changefreq: 'daily', exclude: false }

Devtools

In development, press these shortcuts:

Environment Variables

Client-safe prefixes: VITE_*, EXPO_PUBLIC_*, ONE_PUBLIC_*.

Platform Support

• Web: Browser via Vite
• iOS: React Native via Metro (recommended) or Vite
• Android: React Native via Metro (recommended) or Vite
• Not supported: Windows, Bun runtime for development