Edge runtime

An edge runtime is the lightweight JS / Wasm runtime (V8 isolates, Workerd, Deno, Bun) running app code at network edge POPs — Vercel Edge, Cloudflare Workers, Netlify Edge, Deno Deploy are 2026 leaders.

Edge runtimes are stripped-down JS environments running globally at network POPs near users. Differences from Node.js: subset of standard library (no fs, no native modules), fast cold start (< 5ms vs Node 100ms+), strict CPU + memory limits per request, V8 isolates (Vercel, Cloudflare) or Deno (Netlify). Use cases: auth checks (closer to user = less round-trip), A/B routing, AI streaming proxies, geo personalization, image transformation. Trade-offs: limited runtime restricts library choice (no Postgres pg, no Node-only deps), cold-start is fast but workers can be killed mid-request. AI streaming is the killer app in 2026 — edge runtimes shine for proxy + stream from LLM to user.

When to use edge runtime

• Auth, geo-routing, A/B tests.
• AI streaming proxies.

Common mistakes

• Trying to use Node-only deps — most libraries won't load in edge runtime.
• Running heavy compute — CPU caps will kill workers.

FAQ

Related terms

• Edge function — An edge function is a small serverless function that runs at the network edge — geographically close to the user — typically on Cloudflare Workers, Deno Deploy, Vercel Edge, or AWS Lambda@Edge.
• Serverless GPU — Serverless GPU is the infrastructure model where you submit a job or hit an endpoint and the platform provisions GPU compute on demand, scaling to zero when idle — Modal, Replicate, RunPod, Fal.ai, Cerebrium are 2026 leaders.

Last updated: 2026-06-01. Raw markdown: https://promtable.com/glossary/edge-runtime.md.