Static Assets

Cloudflare Static Assets

Serve static files, single-page applications (SPAs), and build hybrid Workers that combine API routes with frontend hosting.

FIRST: Project Setup

Static Assets require a public/ directory and configuration in wrangler.jsonc:

# Create public directory for your build output
mkdir public

# Add your static files
echo "<h1>Hello World</h1>" > public/index.html

When to Use

Quick Reference

wrangler.jsonc Configuration

Basic Static Hosting

{
  "name": "my-static-site",
  "compatibility_date": "2024-01-01",
  "assets": {
    "directory": "./public/"
  }
}

SPA with Custom 404 Handling

{
  "name": "my-spa",
  "compatibility_date": "2024-01-01",
  "assets": {
    "directory": "./public/",
    "not_found_handling": "single-page-application"
  }
}

not_found_handling options:

• "single-page-application" - Routes all 404s to /index.html (default for SPAs)
• "404-page" - Serves /404.html for missing files
• "none" - Returns standard 404 responses

Hybrid Worker with Static Assets

Combine API routes with static file serving in a single Worker:

// src/index.ts

interface Env {
  ASSETS: Fetcher;
}

export default {
  fetch(request, env) {
    const url = new URL(request.url);

    // Handle API routes in the Worker
    if (url.pathname.startsWith("/api/")) {
      return Response.json({
        name: "Cloudflare",
        timestamp: Date.now()
      });
    }

    // Serve static assets for all other routes
    return env.ASSETS.fetch(request);
  },
} satisfies ExportedHandler<Env>;

wrangler.jsonc for hybrid app:

{
  "name": "my-app",
  "main": "src/index.ts",
  "compatibility_date": "2024-01-01",
  "assets": {
    "directory": "./public/",
    "not_found_handling": "single-page-application",
    "binding": "ASSETS"
  },
  "observability": {
    "enabled": true
  }
}

SPA Routing

Single-page applications need all routes to resolve to index.html for client-side routing to work:

{
  "assets": {
    "directory": "./public/",
    "not_found_handling": "single-page-application"
  }
}

What this does:

• / → serves /index.html
• /about → serves /index.html (client-side router handles /about)
• /contact → serves /index.html
• /styles.css → serves actual file if it exists
• Missing file → serves /index.html

API Routes Pattern

Common pattern: Handle API requests in Worker, serve everything else as static assets:

interface Env {
  ASSETS: Fetcher;
  DB: D1Database;
}

export default {
  async fetch(request, env) {
    const url = new URL(request.url);

    // API Routes
    if (url.pathname.startsWith("/api/")) {
      switch (url.pathname) {
        case "/api/users":
          const users = await env.DB.prepare("SELECT * FROM users").all();
          return Response.json(users.results);
        
        case "/api/health":
          return Response.json({ status: "ok" });
        
        default:
          return Response.json({ error: "Not found" }, { status: 404 });
      }
    }

    // Static Assets
    return env.ASSETS.fetch(request);
  },
} satisfies ExportedHandler<Env>;

Framework Integration

Vite (React, Vue, Svelte)

# Build output goes to dist/
npm run build

# Move to public/
mv dist/* public/

vite.config.ts:

export default {
  build: {
    outDir: 'public'
  }
}

Next.js (Static Export)

npm run build

next.config.js:

module.exports = {
  output: 'export',
  distDir: 'public'
}

Remix

npm run build

remix.config.js:

module.exports = {
  assetsBuildDirectory: "public/build"
}

ASSETS Fetcher API

The ASSETS binding is a Fetcher that handles static file requests:

interface Env {
  ASSETS: Fetcher;
}

// Direct pass-through
env.ASSETS.fetch(request)

// Modify request before serving
const modifiedRequest = new Request(request.url, {
  headers: { "Cache-Control": "max-age=3600" }
});
env.ASSETS.fetch(modifiedRequest)

// Serve specific file
env.ASSETS.fetch(new Request("https://example.com/index.html"))

Cache Control

Static assets are cached by default. Customize caching behavior:

export default {
  async fetch(request, env) {
    const url = new URL(request.url);
    
    // API routes - no cache
    if (url.pathname.startsWith("/api/")) {
      return Response.json({ data: "dynamic" }, {
        headers: { "Cache-Control": "no-store" }
      });
    }
    
    // Get asset response
    const response = await env.ASSETS.fetch(request);
    
    // Customize cache headers for specific files
    if (url.pathname.endsWith(".js") || url.pathname.endsWith(".css")) {
      const newResponse = new Response(response.body, response);
      newResponse.headers.set("Cache-Control", "public, max-age=31536000, immutable");
      return newResponse;
    }
    
    return response;
  },
} satisfies ExportedHandler<Env>;

Detailed References

• references/configuration.md - Full assets configuration options, binding details
• references/frameworks.md - Framework-specific build configurations
• references/testing.md - buildPagesASSETSBinding, testing SPA fallback, ASSETS binding

Best Practices

1. Use SPA mode for client-side routing: Set "not_found_handling": "single-page-application"
2. Prefix API routes: Use /api/* pattern for clear separation from static routes
3. Configure framework output: Point build output directly to ./public/
4. Cache immutable assets: Add cache headers for hashed files (app.abc123.js)
5. Enable observability: Track Worker analytics with "observability": { "enabled": true }
6. Test locally: Use wrangler dev to test both Worker and assets together
7. Handle errors gracefully: Return proper status codes for API routes vs static assets

Common Patterns

Authentication Check Before Assets

export default {
  async fetch(request, env) {
    const url = new URL(request.url);
    
    // Public routes
    if (url.pathname === "/login" || url.pathname.startsWith("/public/")) {
      return env.ASSETS.fetch(request);
    }
    
    // Check authentication
    const token = request.headers.get("Authorization");
    if (!token) {
      return new Response("Unauthorized", { status: 401 });
    }
    
    // API or authenticated assets
    if (url.pathname.startsWith("/api/")) {
      return handleAPI(request, env);
    }
    
    return env.ASSETS.fetch(request);
  },
};

Custom Error Pages

export default {
  async fetch(request, env) {
    const url = new URL(request.url);
    
    if (url.pathname.startsWith("/api/")) {
      try {
        return await handleAPI(request, env);
      } catch (error) {
        return Response.json({ error: error.message }, { status: 500 });
      }
    }
    
    const response = await env.ASSETS.fetch(request);
    
    // Serve custom 404 page
    if (response.status === 404) {
      return env.ASSETS.fetch(new Request(`${url.origin}/404.html`));
    }
    
    return response;
  },
};

Local Development

# Start dev server with assets
wrangler dev

# Specify custom port
wrangler dev --port 8787

# Auto-rebuild on changes (if using framework)
# Terminal 1: Framework watch mode
npm run dev

# Terminal 2: Wrangler
wrangler dev

Deployment

# Deploy Worker + Assets together
wrangler deploy

# View deployment
wrangler deployments list

The Worker and static assets are deployed as a single unit. All files in the assets.directory are uploaded and served from Cloudflare's global network.