Juntos

Rails patterns, JavaScript runtimes.

Write Rails applications that run everywhere: browsers, Node.js, Bun, Deno, Cloudflare Workers, and Vercel Edge Functions. Same models, controllers, and views—different runtimes.

Quick Start

npx github:ruby2js/juntos --demo blog
cd blog
npx juntos dev -d dexie
npx juntos test

That's it. Open http://localhost:5173 to see your app.

Run Anywhere

Juntos (no Ruby required):

npx juntos dev -d dexie      # Browser with IndexedDB
npx juntos up -d sqlite      # Node.js with SQLite
npx juntos deploy -d neon    # Vercel Edge
npx juntos deploy -d d1      # Cloudflare Workers

Also deploys to mobile (Capacitor) and desktop (Electron, Tauri)—platforms Rails can't reach. See Deployment Guide.

Rails (requires Ruby):

bundle install
bin/rails db:prepare
bin/rails server

Add to Existing Project

Initialize Juntos in an existing project:

npx github:ruby2js/juntos init              # Current directory
npx github:ruby2js/juntos init my-app       # Specific directory

This creates the configuration files needed for Juntos:

• package.json (or merges dependencies into existing)
• vite.config.js
• vitest.config.js
• test/setup.mjs
• bin/juntos

Live Demos

Try them in your browser — no install required.

Available Demos

Demo	Description
blog	Articles and comments with real-time updates
chat	Real-time messaging with Turbo Streams
notes	JSON API with React frontend
photo-gallery	Device APIs and Electron support
dictaphone	Audio recording with AI transcription and Active Storage
workflow	React Flow integration
ssg-blog	Static site generation with 11ty
astro-blog	Content with client-side functionality

npx github:ruby2js/juntos --demo chat
npx github:ruby2js/juntos --demo notes my-notes  # Custom directory
npx github:ruby2js/juntos --demo blog --no-install  # Skip npm install

Try Without Ruby

Verify everything works with just Node.js using Docker:

docker run -it --rm -p 5173:5173 -p 3000:3000 node:22 bash -c '
  cd /tmp &&
  npx github:ruby2js/juntos --demo blog &&
  cd blog &&
  echo "Ready. Try: npx juntos dev -d dexie" &&
  exec bash
'

Then inside the container:

npx juntos test           # Run tests
npx juntos dev -d dexie   # Dev server → http://localhost:5173
npx juntos up -d sqlite   # Production → http://localhost:3000

No Ruby installed. Rails patterns just work.

Documentation

https://www.ruby2js.com/docs/juntos

How It Works

Juntos transpiles Ruby to JavaScript using Ruby2JS. Your Rails models, controllers, and views become JavaScript that runs anywhere.

• Models → JavaScript classes with ActiveRecord-like queries
• Controllers → Request handlers with before_action, params, flash
• Views → ERB templates become JavaScript render functions
• Routes → Rails-style routing with path helpers

No lock-in: npx juntos eject writes the transpiled JavaScript to disk. You can continue development in pure JavaScript without ever touching Ruby again.

License

MIT