# For local development, create .dev.vars:
echo "ANTHROPIC_API_KEY=your-api-key-here" > .dev.vars

# For production, use wrangler secrets:
npx wrangler secret put ANTHROPIC_API_KEY

3. Local Development

# Start development server (requires Docker)
npm run dev

# In another terminal, test the endpoint:
curl -X POST http://localhost:8787/execute \
  -H "Content-Type: application/json" \
  -d '{"question": "What is the 10th Fibonacci number?"}'

4. Deploy to Cloudflare

# Deploy worker
npx wrangler deploy

# Wait 2-3 minutes for container provisioning
npx wrangler containers list

# Test production endpoint
curl -X POST https://your-worker.your-subdomain.workers.dev/execute \
  -H "Content-Type: application/json" \
  -d '{"question": "Calculate factorial of 5"}'

Architecture

This sandbox combines three powerful technologies:

Claude AI (Anthropic) - Generates executable code from natural language
Cloudflare Workers - Runs at the edge for global low-latency access
Sandbox SDK - Provides isolated container execution

User Question → Cloudflare Worker → Claude AI → Generated Code → Sandbox → Results

API Reference

POST /execute

Execute a natural language question as code.

Request:

{
  "question": "What is the 100th Fibonacci number?",
  "maxTokens": 2048,          // Optional: Max tokens for code generation
  "timeout": 30000,            // Optional: Execution timeout in ms
  "language": "python"         // Optional: "python" or "javascript"
}

Response:

{
  "success": true,
  "question": "What is the 100th Fibonacci number?",
  "code": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)\n\nprint(fibonacci(100))",
  "output": "354224848179261915075\n",
  "error": "",
  "sandboxId": "user-1234567890-abc123",
  "executionTime": 2147
}

GET /health

Check worker health status.

Response:

{
  "status": "healthy",
  "timestamp": "2025-10-19T12:00:00.000Z",
  "worker": "cloudflare-claude-sandbox"
}

Command Line Tools

Launcher

Execute prompts directly from command line:

# Basic usage
node launcher.ts "Calculate factorial of 5"

# With custom worker URL
node launcher.ts "Fibonacci 10" "" your_api_key https://your-worker.workers.dev

# With components
node launcher.ts "Create a React app" "--agent frontend-developer" your_api_key

Monitor

Monitor execution with detailed metrics:

# Monitor execution
node monitor.ts "Calculate factorial of 5" your_api_key

# Monitor production worker
node monitor.ts "Sum array" your_api_key https://your-worker.workers.dev

Examples

Mathematical Calculations

curl -X POST http://localhost:8787/execute \
  -H "Content-Type: application/json" \
  -d '{"question": "What is the factorial of 20?"}'

String Manipulation

curl -X POST http://localhost:8787/execute \
  -H "Content-Type: application/json" \
  -d '{"question": "Reverse the string Hello World"}'

Data Analysis

curl -X POST http://localhost:8787/execute \
  -H "Content-Type: application/json" \
  -d '{"question": "Calculate the mean of [10, 20, 30, 40, 50]"}'

JavaScript Execution

curl -X POST http://localhost:8787/execute \
  -H "Content-Type: application/json" \
  -d '{
    "question": "Sort an array of numbers",
    "language": "javascript"
  }'

Configuration

Environment Variables

Local Development (.dev.vars):

ANTHROPIC_API_KEY=sk-ant-your-key-here

Production (Wrangler Secrets):

npx wrangler secret put ANTHROPIC_API_KEY

Wrangler Configuration

Edit wrangler.toml to customize:

# Worker name (must be unique)
name = "my-custom-sandbox"

# Resource limits
[limits]
cpu_ms = 100  # CPU time per request

# Environment-specific configuration
[env.production]
vars = { ENVIRONMENT = "production" }

Troubleshooting

Container Not Ready

After first deployment, wait 2-3 minutes:

npx wrangler containers list

Docker Issues (Local Development)

Ensure Docker is running:

docker ps

API Key Not Set

For local development:

echo "ANTHROPIC_API_KEY=your-key" > .dev.vars

For production:

npx wrangler secret put ANTHROPIC_API_KEY

View Logs

# Real-time logs
npx wrangler tail

# Pretty formatted
npx wrangler tail --format=pretty

Performance Tips

Use specific prompts: More specific questions generate faster code
Implement caching: Cache generated code for common questions
Stream output: Use streaming for long-running operations
Set appropriate timeouts: Balance between UX and resource usage
Monitor metrics: Use the monitor tool to identify bottlenecks

Security

Sandboxes are isolated containers with no network access
Code execution is limited by timeout (default 30s)
CPU and memory limits are enforced by Cloudflare
API keys are stored as encrypted Wrangler secrets
CORS is enabled for browser access (configure as needed)

Cost Estimation

Cloudflare Workers:

Free tier: 100,000 requests/day (limited Durable Objects)
Paid plan ($5/month): 10M requests/month + unlimited Durable Objects

Anthropic API:

Claude Sonnet 4.5: ~$3 per million input tokens
Average request: ~200 tokens = $0.0006 per request

Example costs for 10,000 requests/month:

Cloudflare: $5/month (paid plan)
Anthropic: ~$6/month (avg 200 tokens/request)
Total: ~$11/month

Development

Project Structure

cloudflare-claude-sandbox/
├── src/
│   └── index.ts           # Worker source code
├── launcher.ts            # CLI launcher tool
├── monitor.ts             # Monitoring tool
├── wrangler.toml          # Cloudflare configuration
├── package.json           # Dependencies
├── tsconfig.json          # TypeScript config
└── README.md              # This file

Scripts

npm run dev - Start local development server
npm run deploy - Deploy to Cloudflare
npm run tail - View real-time logs
npm run launch - Run launcher tool
npm run monitor - Run monitoring tool
npm run type-check - Check TypeScript types
npm test - Run tests

Resources

License

MIT License - See LICENSE file for details

Support

For issues and questions:

Check the debugging guide
Run the monitor tool for detailed metrics
Check Cloudflare worker logs: npx wrangler tail
Open an issue on GitHub

Built with ❤️ using Cloudflare Workers, Claude AI, and the Sandbox SDK