Can I move WebContainer API code to Uncontained?

Yes. @uncontained/webcontainer-compat keeps boot, mount, spawn and server-ready. Change the import and keep the rest.

Does Uncontained need COOP and COEP headers too?

Yes. The page that embeds the machine is cross-origin isolated, the same requirement WebContainers has. Cross-Origin-Embedder-Policy can be require-corp or credentialless.

What runs that WebContainers cannot run?

Bun, native Node addons, apt packages, raw TCP clients for databases, and any unmodified arm64 Linux program, such as Python 3.13 with pip, Go and gcc.

A WebContainers alternative with a real Linux kernel

Node, Bun and any arm64 Linux program in the tab, with the WebContainer API kept for code you already wrote.

Try it in your browser

$npm i @uncontained/sdk

$yarn add @uncontained/sdk

$pnpm add @uncontained/sdk

$bun add @uncontained/sdk

$deno add npm:@uncontained/sdk

Uncontained vs WebContainers, side by side

WebContainers, from StackBlitz, is a browser runtime for Node.js applications. StackBlitz does not claim a Linux kernel, and native addons are off.

Uncontained compared with WebContainers
Capability	Uncontained	WebContainers
Real Linux kernel	Yes, Linux 6.18	No
Unmodified native binaries	Yes, any arm64 Linux program	No
Native Node addons (N-API)	Yes	No, unless built to WebAssembly
Node.js	26.13.0 on the browser’s JIT	24.22.2 by default
Bun	1.4.4	Not supported; request open since 3 June 2025
apt and Debian packages	Yes, Debian 13	No; npm, pnpm and yarn v1
Raw TCP, UDP and TLS sockets	Yes	No
WebAssembly	WASI 0.1, 0.2, 0.3, WASIX and the wasmer CLI	WASI, version not stated
Claude Code and other coding agents	Yes, on native JS	Not documented

WebContainers facts are from StackBlitz’s own pages, read on 10 November 2026.

When WebContainers is the better fit

WebContainers is a hosted runtime with years of use in StackBlitz for Node web tooling. If your app only runs JavaScript tools in Chromium and you want StackBlitz to host the engine, it is the shorter path.

Questions about switching from WebContainers

Can I move WebContainer API code to Uncontained?: Yes. @uncontained/webcontainer-compat keeps boot, mount, spawn and server-ready. Change the import and keep the rest.
Does Uncontained need COOP and COEP headers too?: Yes. The page that embeds the machine is cross-origin isolated, the same requirement WebContainers has. Cross-Origin-Embedder-Policy can be require-corp or credentialless.
What runs that WebContainers cannot run?: Bun, native Node addons, apt packages, raw TCP clients for databases, and any unmodified arm64 Linux program, such as Python 3.13 with pip, Go and gcc.