Edge network — Domainee Glossary

Distributed servers close to users that terminate TLS, run cache, and sometimes execute code. The serving layer in front of your origin.

An edge network is the layer of globally distributed servers that sits between users and your origin. Each "edge" is a data center or PoP (Point of Presence) close to a user population, configured to terminate TLS, run caching, execute serverless code, and route to the right origin.

The line between "CDN" and "edge network" has blurred. Cloudflare started as a CDN and now runs Workers (code at the edge). Fastly does the same with Compute@Edge. Vercel and Netlify deploy frontend code to edges. AWS CloudFront added Lambda@Edge. For practical purposes, modern "CDN" = "edge network."

What lives at the edge

TLS termination. Cert lives at the edge. SSL handshake completes there, not at origin. Means your origin only sees plain HTTP from a trusted source.
Caching. As in any CDN.
WAF (Web Application Firewall). Block malicious requests before they reach origin.
Rate limiting. Apply per-IP, per-user, per-path limits.
Edge functions. Run serverless code on the request: rewrite headers, perform A/B routing, do auth checks, modify the body. Cloudflare Workers, Vercel Edge Functions, Fastly Compute@Edge.
Routing. Pick the right origin region based on user geo or origin health.

Why an edge network helps a custom-domain SaaS

When customers point their domain at your platform, the request path is:

user → DNS resolution → your edge → your app

The edge gives you:

One cert per customer hostname, automatic. Edge handles issuance and renewal.
DDoS absorption. Edge has 100x your origin's bandwidth.
SNI-based routing. Map customer hostname to customer-specific config (cache rules, headers, origin selection).
Low TLS handshake latency. TLS 1.3 + edge geographic proximity = sub-50ms TTFB for the first byte of TLS.

Without an edge, every customer hostname has to hit your origin, your origin has to terminate TLS, your origin's load balancer has to handle a much larger fan-in. Hard to scale, costly to operate.

Building vs buying

Building your own edge is heavy: 5+ PoPs minimum to be credible, ACME automation, anycast IPs, BGP peering, DDoS scrubbing. Capital and operational cost dwarfs most SaaS budgets.

Buying:

Cloudflare for SaaS.
Fastly Real-Time Customer Hostnames.
AWS CloudFront + Certificate Manager (more DIY).
Approximating: Vercel, Netlify, Render with their custom-domain offerings (good for smaller scale).
Domainee.

For a custom-domain SaaS with 100-10,000 customer hostnames, buying edge service is usually the right call.