Use Case: Large File Sharing with Watermark Protection

The Challenge

Imagine you’re running a digital asset management platform where clients download large collections of design files, photos, or marketing materials. You face several critical challenges:

1. Storage Costs: Storing pre-generated ZIP files for every possible file combination is expensive and inefficient
2. Protection Needs: You want to add watermark text files or licensing information to each download
3. Large File Sizes: Collections often exceed several gigabytes
4. Dynamic Content: File sets change frequently, making pre-generated archives obsolete quickly

Traditional solutions require you to:

• Generate and store ZIP files in advance (expensive storage)
• Or buffer entire files in memory before sending (high memory usage, slow start times)
• Maintain separate copies with different watermarks for different users

The ZipStream Solution

ZipStream allows you to dynamically create ZIP archives on-the-fly without storing them or buffering the entire content in memory. Here’s how it solves the watermark use case:

Architecture

Client Request → ZipStream API → Stream Multiple URLs + Watermark → ZIP Download

Implementation Example

curl -X POST https://zipstream.app/api/downloads \
  -H "Content-Type: application/json" \
  -d '{
    "suggestedFilename": "client-assets-2024.zip",
    "files": [
      {
        "url": "https://cdn.example.com/designs/logo-v1.psd",
        "zipPath": "designs/logo-v1.psd"
      },
      {
        "url": "https://cdn.example.com/designs/banner.ai",
        "zipPath": "designs/banner.ai"
      },
      {
        "url": "https://cdn.example.com/photos/product-001.jpg",
        "zipPath": "photos/product-001.jpg"
      },
      {
        "url": "https://yourserver.com/watermarks/client-123-license.txt",
        "zipPath": "LICENSE.txt"
      },
      {
        "url": "https://yourserver.com/watermarks/client-123-terms.pdf",
        "zipPath": "TERMS_OF_USE.pdf"
      }
    ],
    "compression": "STORE"
  }' \
  --output client-assets.zip

Key Benefits

1. Zero Storage Overhead

• No need to pre-generate or store ZIP files
• Files are streamed directly from your CDN or storage
• Watermark files are generated dynamically per client

2. Memory Efficient

• Files are streamed, not buffered
• Can handle multi-gigabyte archives without memory issues
• Server resource usage remains constant regardless of archive size

3. Dynamic Watermarking

Each client gets personalized watermark files:

// Generate client-specific watermark on your server
app.get('/watermarks/:clientId-license.txt', (req, res) => {
  const { clientId } = req.params;
  const client = getClientInfo(clientId);

  const watermark = `
This content is licensed to: ${client.company}
License ID: ${client.licenseId}
Valid until: ${client.expiryDate}
Authorized user: ${client.email}

This material is protected by copyright law.
Unauthorized distribution is prohibited.
  `;

  res.type('text/plain').send(watermark);
});

4. Cost-Effective at Scale

• Storage savings: No duplicate ZIP files
• Bandwidth optimization: Use compression: "STORE" for already-compressed files (PSDs, JPGs, PDFs)
• CPU efficiency: No compression overhead for binary files

Real-World Example

Scenario: Photography studio with 10,000 clients, each downloading custom collections

Traditional Approach: - Average collection: 2GB (50 photos + watermarks) - Pre-generated ZIPs: 10,000 × 2GB = 20TB storage - Cost: ~$400/month on S3 Standard

ZipStream Approach: - Store original photos once: 100GB - Generate watermarks on-demand: <1MB - Total storage: 100GB - Cost: ~$2.30/month on S3 Standard - Savings: $397.70/month (99.4% reduction)

Advanced Features

File Validation Before Download

# Validate all files are accessible before starting download
curl -X POST "https://zipstream.app/api/downloads?validate=true" \
  -H "Content-Type: application/json" \
  -d '{"files": [...]}'

This prevents incomplete downloads if any source file is inaccessible.

Size Estimation

# Check total size before initiating download
curl -X POST https://zipstream.app/api/size-estimates \
  -H "Content-Type: application/json" \
  -d '{
    "files": [
      {"url": "https://cdn.example.com/large-file.psd", "zipPath": "file.psd"}
    ]
  }'

Response:

{
  "estimatedTotalSize": 2147483648,
  "formattedSize": "2.0 GB",
  "files": 25
}

Temporary Download Links

For secure, expiring download links:

# Create a 60-second temporary link
curl -X POST https://zipstream.app/api/download-links \
  -H "Content-Type: application/json" \
  -d '{
    "files": [
      {"url": "https://cdn.example.com/file.jpg", "zipPath": "file.jpg"},
      {"url": "https://yourserver.com/watermark.txt", "zipPath": "LICENSE.txt"}
    ]
  }'

Response:

{
  "status": "ok",
  "linkId": "550e8400-e29b-41d4-a716-446655440000",
  "downloadUrl": "/api/download-links/550e8400-e29b-41d4-a716-446655440000",
  "expiresIn": 60
}

Best Practices

1. Use STORE compression for media files: Photos, videos, PSDs are already compressed. Re-compressing wastes CPU.
2. Host watermarks on fast servers: Keep watermark files on your application server for quick access
3. Validate before large downloads: Use ?validate=true for collections over 1GB
4. Rate limiting awareness: Default limit is 10 requests/hour per IP. Plan accordingly for high-traffic scenarios.
5. CDN integration: Serve source files from a CDN for best performance

Technical Specifications

Feature	Limit
Max files per archive	50 files
Max total size	5GB
Rate limit	10 requests/hour per IP
Burst limit	5 requests per 10 minutes
Link expiration	60 seconds (temporary links)

Security Considerations

1. Access Control: Keep your watermark URLs private or implement authentication
2. HTTPS Only: Always use HTTPS for source URLs to prevent interception
3. Temporary Links: Use download links API for time-limited access
4. Rate Limiting: Built-in rate limiting prevents abuse

Conclusion

ZipStream transforms the economics of large file distribution with watermark protection. By eliminating storage overhead and enabling dynamic watermarking, you can:

• Save 99%+ on storage costs for archive files
• Personalize every download without pre-generation
• Scale effortlessly to millions of unique combinations
• Deliver instantly without buffering delays

Whether you’re running a digital asset platform, photography studio, or design marketplace, ZipStream provides the infrastructure to deliver protected content efficiently and economically.

---

Ready to try it? Visit zipstream.app to start building dynamic ZIP archives today.