# Edge runtime

**Source:** https://promtable.com/glossary/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.

---
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

- 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.

## Related terms

- [edge-function](https://promtable.com/glossary/edge-function)
- [serverless-gpu](https://promtable.com/glossary/serverless-gpu)

*Last updated: 2026-06-01*
---

Original page: https://promtable.com/glossary/edge-runtime
Maintained by Promtable (https://promtable.com). Content: CC BY 4.0. Cite as "Promtable — https://promtable.com/glossary/edge-runtime".
Contact: info@vibecodingturkey.com.