Legacy Sandboxes


Configuration Files

There are some advanced use cases where you might need more control over a sandbox or template. That's why we support configuration files. Every template on CodeSandbox has a list of configuration files it supports. You can see the supported files under Configuration Files from the left-hand activity bar in the editor.

Configurations File UI

Configuration UI

Some configuration files can be configured using a UI. This UI will generate a configuration file based on its state.

Configurations File UI

Sandbox Configuration

A sandbox can be configured too, you can do this with sandbox.config.json. We support these options:

OptionDescriptionPossible ValuesDefault Value
infiniteLoopProtectionWhether we should throw an error if we detect an infinite looptrue / falsetrue
hardReloadOnChangeWhether we should refresh the sandbox page on every change, good for sandboxes with global statetrue / falsefalse
templateWhich sandbox template to usesee here (opens in a new tab)smart detection, w/ fallback to "create-react-app"
viewWhich view to show first in the previewClient: "browser" / "console" / "problems" / "tests"
Container: "browser" / "console" / "problems" / "terminal"
disableLoggingWhether we should disable in-browser logging and have all logs created by the sandbox go to the browser consoletrue / falsefalse

Container Configuration


Container Sandboxes are deprecated for Devboxes. You can find more info about configuring Devboxes here.

OptionDescriptionPossible ValuesDefault Value
containerThe container object contains the port, start script and Node.js major version, for example: "container": { "port": 3212, "startScript": "custom", "node": "14" }
portThe main port which the browser window listens to1024 - 65535First opened port inside the container.
startScriptExplicitly specify the start script used in a container sandbox, overriding the default valueA String matching a script name defined under "scripts" in package.json"dev" / "develop" / "serve" / "start"
nodeThe Node.js major version to use inside the container. The exact versions used are as follows:
"10": 10.24.1
"12": 12.22.7
"14": 14.18.1
"16": 16.12.0
"10" / "12" / "14" / "16""14"