Modal Sandboxes vs SPACE

Modal Sandboxes

GPU sandboxes at the same per-second rates as the rest of Modal. No REST API, and the JavaScript and Go SDKs are beta.

SPACE

Once deployed, SPACE's native API has a public OpenAPI 3.1 contract, stable error codes with a retryable flag and 24-hour idempotency keys, and egress and credential controls sit outside the VM. A person must first deploy it on a Linux x86_64 host with KVM and Kubernetes. Version 0.8.0 has no tagged release, changelog or public container images.

Modal Sandboxes

1. Pass timeout= when you create a sandbox. The default lifetime is 5 minutes
2. Set block_network=True or a cidr_allowlist for untrusted code
3. Give a sandbox a name so a retried create raises AlreadyExistsError instead of starting a second one
4. Snapshot the filesystem before the 24-hour limit and start a fresh sandbox from it
5. Catch ResourceExhaustedError from Sandbox.create() on SDK 1.6.0 and later

SPACE

1. Ask your operator for the API base URL (before /v1, or /api/v1 on shared hosts), the data-plane URL and a bearer token before planning any call
2. Poll the returned operation until it succeeds and the sandbox is running before creating a command. A 202 response is not readiness
3. Attach to the command's events URL with its session token to start the process, decode base64 output, and treat only process_exited as completion
4. Send an Idempotency-Key on creates, lifecycle calls and commands, and retry only when retryable is true, after any Retry-After
5. Save output as it arrives. Reconnecting with Last-Event-ID returns resync_required, not the missed output