Blaxel Sandboxes vs Cloudflare Sandbox SDK

Blaxel Sandboxes

No compute charge in standby, only $0.20 a GB-month of snapshot storage. 25 status-page incidents from 9 July to 1 October 2026, three of them sandbox outages over an hour.

Cloudflare Sandbox SDK

Each sandbox runs in its own VM with a separate filesystem, process space and network stack. No hosted API. You deploy and secure a Worker before an agent can call anything, and the starter has no auth.

Blaxel Sandboxes

1. Close WebSocket and terminal connections when done. An open connection keeps the sandbox active and billed
2. Set a TTL or idle expiry on throwaway sandboxes. The default is to keep them
3. Set forbiddenDomains or an allow list at creation, with network.firewall for tools that ignore proxy settings. Both can only be set when the sandbox is created
4. Retry only on WORKLOAD_UNAVAILABLE. The error reference says other codes won't succeed on retry
5. Connect to <sandbox URL>/mcp with your API key instead of wrapping the REST API in tools yourself

Cloudflare Sandbox SDK

1. Derive the sandbox ID from the authenticated user, as the docs advise. IDs aren't secrets
2. Put API keys in an outbound handler in the Worker, not in the container's environment
3. Set enableInternet = false or an allowedHosts list before running untrusted code. Internet access is on by default
4. Check that a restored backup has every directory you expect. Backups of 10 MB or more have open bugs
5. Start new projects on 1.0. The 0.x library only gets fixes until 31 December 2026