Sandboxes overview

A sandbox is a lightweight virtual machine, built on the open-source Firecracker hypervisor, that starts in about a second and runs a single container-style workload: an AI coding agent, a code runner, a small web app, or a CI job runner. Sandboxes are billed by the second or by the minute rather than by the month, and most of them are meant to be short-lived.

Where to find it

In the user panel, sandboxes live under their own Sandboxes section: Kits, Sandboxes, Connectors, API keys, Secrets and Tools.

From kit to sandbox

Kit: the template a sandbox launches from. Some kits are ready-made agent kits such as Claude Code or Codex CLI; others are platform base kits or kits you build yourself from a Dockerfile, a container image reference, or a Git repository. See Create a kit.
Kit version: every build of a kit produces a new version. The current version is what new sandboxes use by default.
Sandbox: a running (or paused, or stopped) instance of a kit version, with its own size, network and lifecycle settings. You start one from the launcher; see Launch a sandbox.
Secrets: API keys and other values your sandboxes need, kept encrypted in your account and handed to a sandbox at launch. See Agent kits.
Tools: external tool servers (MCP servers) that an agent in the sandbox can call, with the provider’s credentials managed by the panel and delivered to the node gateway rather than to the sandbox. See Tools (MCP).
Connector: an integration that launches sandboxes automatically as CI runners in response to GitHub Actions or GitLab CI jobs. See Connectors.

How long a sandbox stays up

Every sandbox has three independent settings that control its lifetime. In the launcher they are chosen in one place, the lifetime part of the launch sentence:

Maximum lifetime: a hard cap on how long the sandbox runs, counted from creation. You can pick 15 minutes, 1 hour, 4 hours or 8 hours, or a custom length. When it elapses, the sandbox is either paused or deleted, depending on When the time is up.
When the time is up: Pause keeps the sandbox’s state on disk so it can be resumed later, or Stop and delete removes it outright.
Idle pause: pauses a sandbox automatically after it has been idle for a while (the launcher offers 10 idle minutes), independent of the maximum lifetime.

Never stops on its own (always on) exempts a sandbox from idle pause and keeps it in continuous use; a platform housekeeping job restarts it automatically if it ever lands in an error state.

Networking and ingress

Every sandbox has a public network, a VPC network, or both - there is no way to create one with no network at all. A public network gets an automatically assigned public IPv4 (or one of your own static IPs); a VPC network gets a private address from one of your VPC subnets, with outbound internet through that VPC’s NAT gateway. See Networking for the full model. On top of that, HTTP ingress can expose one port (plus extra ports) to the internet at an automatically generated hostname or a custom domain, and shell ingress opens an interactive web terminal. Shell ingress needs a kit that includes envd, such as sandbox-base or another kit marked as supporting the web shell; see Web shell, logs and metrics.