CDN edge
A CDN edge is one of the geographically distributed points-of-presence operated by a content delivery network — typically hundreds of locations worldwide where static and cacheable content is served from the location closest to the user. The edge layer cuts latency dramatically vs origin-served content and offloads origin traffic.
Modern CDN edges do more than cache static assets: they terminate TLS, run edge functions, handle image transformations, perform redirects, route requests to the optimal origin, and apply security rules (WAF, bot detection). The major CDNs (Cloudflare, Fastly, Akamai, CloudFront, Bunny) differ in network footprint, pricing, and runtime capability rather than core caching. For most apps, the right architecture is: static assets cached aggressively at edge, dynamic responses cached selectively (with stale-while-revalidate), and edge functions handling the lightweight personalisation that turns 'cached HTML' into 'feels-personal HTML'.
Related terms
- Edge function
An edge function executes at the CDN's edge locations close to the user — typically with sub-millisecond cold starts (V8 isolates) and ~10-50ms latency advantage vs origin-region functions.
- Static site generation (SSG)
Static site generation pre-renders every page to plain HTML at build time, then serves the HTML directly from a CDN with no server-side execution per request.
- Real user monitoring (RUM)
Real user monitoring (RUM) instruments actual user sessions in the browser or mobile client to capture performance and error metrics as users experience them — Core Web Vitals (LCP, INP, CLS), JavaScript errors, network requests, custom timing marks.