Gzip Compression in CDN Configuration

CDN Compression Configuration

Content Delivery Networks (CDNs) can compress content at the edge, closer to users. Each CDN handles compression differently.

Cloudflare

Cloudflare automatically compresses text-based assets:

• Gzip: Enabled by default for all text content types
• Brotli: Toggle in Dashboard > Speed > Optimization
• Compression level: Not user-configurable (Cloudflare optimizes internally)
• Pre-compressed support: Cloudflare re-compresses regardless

AWS CloudFront

CloudFront supports compression but requires explicit configuration:

{
  "CacheBehavior": {
    "Compress": true,
    "ViewerProtocolPolicy": "redirect-to-https"
  }
}

• Compresses objects between 1,000 and 10,000,000 bytes
• Supports gzip and Brotli (automatic negotiation)
• Origin must NOT set Content-Encoding (CloudFront compresses at edge)

Vercel

Vercel enables compression automatically:

• Brotli: Default for all text assets over HTTPS
• Gzip: Fallback for non-Brotli clients
• No configuration needed — it’s always on
• Static assets are pre-compressed at build time

Fastly

Fastly provides granular control via VCL:

sub vcl_fetch {
  if (beresp.http.Content-Type ~ "text|javascript|json|xml|svg") {
    set beresp.gzip = true;
  }
}

Key CDN Considerations

1. Vary header: CDNs cache different versions based on Accept-Encoding
2. Origin compression: Some CDNs skip re-compression if origin sends compressed content
3. Cache hit ratio: Separate cache entries for gzip/brotli/uncompressed can reduce hit rates
4. Edge compression cost: CDN edge compression adds slight latency but saves bandwidth