Avoid sandboxes

Code-execution sandboxes are not available on Outer — do not ship sandbox code.

Verdict: not available. Do not build on void/sandbox. There is no container runtime behind Outer apps today. Never ship sandbox code. The person-facing page is What your app cannot do yet.

Know why it cannot run

Void sandboxes (getSandbox(id), sandbox.run/files/fetch) are isolated Linux containers fronted by a Durable Object. They need Cloudflare Containers: a container runtime on every machine that can start the app’s image. Outer runs each app as a celld worker fleet: plain processes under cgroup and network isolation, no Docker/Podman daemon on the app host. A sandbox has nowhere to start. The containers wrangler key passes Outer’s deploy validation, so the failure would come at runtime, not at deploy. Do not ship sandbox code expecting the deploy gate to catch it.

Do this instead