Edge Function

ELI5 — The Vibe Check

Edge functions run your code at the CDN edge — meaning close to the user, not in some faraway data center. A user in Tokyo hits your API and it runs on a server in Tokyo. A user in Paris gets a server in Paris. It's serverless functions but geographically distributed. The tradeoff? Limited runtime (no Node.js filesystem, short execution time), but for things like auth, redirects, and personalization, it's blazingly fast.

Real Talk

Edge Functions are serverless compute units that execute at CDN edge locations closest to the requesting user, minimizing network latency. They run in lightweight runtimes (V8 isolates, Deno, or WebAssembly) with fast cold starts (<5ms). Use cases include request routing, A/B testing, authentication, geolocation-based content, and response transformation. Providers include Cloudflare Workers, Vercel Edge Functions, Deno Deploy, and Netlify Edge Functions.

When You'll Hear This

"Put the auth check in an edge function — it runs before the request even hits the origin." / "Edge functions can't do heavy computation, but they're perfect for request transformation."