Building Client-Side Only Sites with Astro + React on Cloudflare Pages

I recently rebuilt my entire tool platform using a client-side only architecture. No server, no API costs, just static HTML/JS deployed globally. Here's how.

Why Client-Side Only?

Traditional server-rendered apps have a hidden cost: the server itself. Even a simple Node.js app needs:

• A server/VPS ($5-10/month minimum)
• Database (often pay-per-query)
• SSL certificates
• Monitoring and maintenance

For many use cases — portfolios, docs, tools, dashboards — you don't need a server at all. The browser can do everything.

The Stack

• Astro: Static site generation with islands architecture
• React: For interactive components when needed
• Cloudflare Pages: Free hosting with global CDN
• Client-side APIs: IndexedDB, localStorage, or external services

Configuration

// astro.config.mjs

export default defineConfig({
  output: 'static', // Key: client-side only
  adapter: cloudflare({
    imageService: 'cloudflare',
  }),
  integrations: [react()],
  vite: {
    ssr: {
      noExternal: ['react', 'react-dom'],
    },
  },
});

The key is output: 'static'. This tells Astro to pre-render everything at build time. No server-side rendering, no serverless functions needed.

Project Structure

/
├── src/
│   ├── components/
│   │   ├── Counter.jsx        // React - hydrated
│   │   ├── Header.astro       // Static, no JS
│   │   └── DataViz.jsx        // React - hydrated
│   ├── layouts/
│   │   └── MainLayout.astro
│   ├── pages/
│   │   ├── index.astro
│   │   ├── dashboard.astro
│   │   └── tools/
│   │       └── index.astro
│   └── styles/
│       └── global.css
├── public/
│   └── data/
│       └── tools.json
└── astro.config.mjs

Interactive Islands

Astro's islands architecture lets you mix static HTML with interactive React components:

---
// src/pages/dashboard.astro
---

<Layout title="Dashboard">
  <div class="stats">
    <p>Static content loads instantly</p>
  </div>
  
  <!-- Only this hydrates -->
  <Counter client:load initial={42} />
  
  <!-- Hydrates when visible -->
  <SearchPanel client:visible />
</Layout>

State Management

For client-side state, keep it simple:

// src/lib/store.js

function createPersistedStore(key, initial) {
  const stored = typeof localStorage !== 'undefined' 
    ? localStorage.getItem(key) 
    : null;
    
  const store = writable(stored ? JSON.parse(stored) : initial);
  
  store.subscribe(value => {
    if (typeof localStorage !== 'undefined') {
      localStorage.setItem(key, JSON.stringify(value));
    }
  });
  
  return store;
}

export const userPrefs = createPersistedStore('prefs', {
  theme: 'dark',
  layout: 'grid'
});

Deploying to Cloudflare Pages

1. Connect your repo to Cloudflare Pages
2. Build settings:
   • Build command: npm run build
   • Build output directory: dist
   • Node version: 18
3. That's it. Free tier includes:
   • 500 builds/month
   • Unlimited sites
   • Global CDN
   • Auto SSL

External API Integration

Need backend logic? Use external APIs instead of running your own server:

// Fetch from external API
async function getToolData() {
  const response = await fetch('https://api.example.com/tools');
  return response.json();
}

// Or use Cloudflare Workers as your API layer
// - Deploy separate from your frontend
// - Only pay for API calls, not static asset serving

Performance Comparison

Metric	Server-Rendered	Client-Side Static
Time to First Byte	150ms	<10ms
CDN Caching	Partial	Full
Cost per month	$5+	$0
Cold Starts	Yes	None

Use Cases That Work

• Dashboards with client-side data fetching
• Tool collections (URL shorteners, generators)
• Documentation sites
• Portfolios with interactive components
• Internal apps behind auth (use client-side auth)

What's Missing

Client-side only isn't right for everything:

• Server-side rendering for SEO-critical content
• WebSocket/real-time (Durable Objects needed)
• Heavy server-side computation
• Rate limiting without external service

Conclusion

For many web projects, you don't need a server. Astro's static output with React islands gives you the best of both worlds: fast initial load with progressive enhancement, deployed for free on Cloudflare Pages.

Your users won't notice, but your wallet will.