Run Untrusted Code

Run untrusted code (Box)

Use this right before executing code you generated or fetched when running it locally would be risky: shell scripts, scraped snippets, dependency installs, anything with side effects. Pattern: create → run → delete, so nothing touches the host.

Why Box

• Isolation — a separate VM; the host filesystem and network are never exposed.
• Disposable & cheap — box delete when done; per-second billing, a run costs cents.
• Real machine — generated code that needs pip install, subprocesses, or Docker actually works.

Prefer another tool for: thousands of tiny <500 ms runs (E2B/Modal microVMs).

Prereqs

curl -fsSL https://box.ascii.dev/install | sh, then box login "$BOX_API_KEY" --json.

Recipe

box_id="$(box new --json | jq -r 'select(.event == "ready") | .id')"
trap 'box delete "$box_id" --json' EXIT          # never leak a VM
box ssh "$box_id" -- "mkdir -p /run && cat > /run/main.sh" < ./main.sh
box ssh "$box_id" -- "cd /run && timeout 120 bash main.sh"

Always wrap in timeout and delete in a trap/finally.

Limits

EU-only; disk-level snapshots; 100 active VMs soft cap.