Edge Caching
Definition
Storing copies of your website content on servers worldwide, so visitors receive data from a location near them.
What is Edge Caching?
Edge caching stores copies of your website content on servers distributed around the world – the "edge" of the network, close to end users. Instead of every request travelling to your origin server, visitors receive content from a nearby edge location.
This is the core technology behind Content Delivery Networks (CDNs).
Why Edge Caching Matters
Physical Distance Matters
Data travels at finite speeds. A UK user requesting content from a US server waits longer than one served from London.
Reduced Latency
Edge servers closer to users dramatically reduce Time to First Byte and overall page speed.
Origin Server Protection
Edge servers handle most traffic, protecting your origin server from overload.
Global Performance Consistency
Users worldwide get similar performance rather than distant visitors suffering longer load times.
How Edge Caching Works
1. Initial Request
A user visits your site. The edge server checks if it has a cached copy.
2. Cache Miss
If not cached (or expired), the edge server fetches from your origin server, stores a copy, and serves the user.
3. Cache Hit
Subsequent requests find the cached copy at the edge. No origin server request needed.
4. Content Updates
When content changes, edge caches are invalidated so they fetch fresh versions.
What Can Be Edge Cached
Typically Cached
- Images
- CSS and JavaScript files
- Fonts
- Static HTML pages
- Video content
Careful Consideration Required
- Dynamic pages
- Personalised content
- User-specific data
- Frequently changing content
Edge Caching Providers
Major CDN Providers
- Cloudflare
- Fastly
- AWS CloudFront
- Akamai
- Bunny.net
Integrated Platforms
- Vercel Edge Network
- Netlify Edge
- Cloudflare Pages
Edge Functions
Modern edge platforms offer edge functions – code that runs at edge locations. This enables:
- Personalisation at the edge
- A/B testing without origin requests
- Geographic-based content
- Authentication at the edge
These expand what's possible with edge caching beyond static content.
Implementation
Most CDN providers make edge caching straightforward:
- Sign up with a provider
- Point your domain to their network
- Configure cache rules
- Content is automatically distributed globally
For many sites, basic setup takes minutes and provides immediate performance improvements.