# WebContainer

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

> WebContainer is StackBlitz's technology that runs a full Node.js environment inside the browser — no cloud VM, instant boot, offline-capable. The foundation behind StackBlitz, Bolt, Claude Artifacts' code-running mode in 2026.

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WebContainer is StackBlitz's technology that runs a full Node.js environment inside the browser — no cloud VM, instant boot, offline-capable. The foundation behind StackBlitz, Bolt, Claude Artifacts' code-running mode in 2026.

WebContainers compile a Node.js runtime + npm + filesystem to WebAssembly, allowing the user's browser to run Node code without any server. Boot time: < 1 second. Offline-capable (runs entirely locally). Used by: StackBlitz (online IDE), Bolt (AI app builder — sister product), Claude Artifacts (running React code in-browser sandbox), embeddable doc demos. Limits: not all native Node deps work (anything requiring native bindings), memory + storage caps per browser tab, no real network (proxied through StackBlitz infrastructure). For AI-first dev tools WebContainers are a magical primitive — instant runnable code from a prompt, no provisioning, no waiting. Cloudflare Workers + Vercel use similar sandboxed runtimes for edge functions.

## When to use

- AI app builders generating runnable code.
- Embeddable live demos in docs / blogs.

## Common mistakes

- Assuming all npm packages work — native bindings fail.
- Trying to run heavy compute — browser CPU caps will kill it.

## Related terms

- [live-preview](https://promtable.com/glossary/live-preview)
- [interactive-artifact](https://promtable.com/glossary/interactive-artifact)
- [edge-runtime](https://promtable.com/glossary/edge-runtime)

## Sources

- [WebContainer API](https://webcontainers.io/)

*Last updated: 2026-06-01*
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Original page: https://promtable.com/glossary/webcontainer
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