# Sandbox metadata

Metadata is a way to attach arbitrary key-value pairs for a sandbox.

This is useful in various scenarios, for example:
- Associate a sandbox with a user session.
- Store custom user data for a sandbox like API keys.
- Associate a sandbox with a user ID and [connect to it later](/docs/sandbox/connect).

You specify metadata when creating a sandbox and can access it later through listing running sandboxes with `Sandbox.list()` method.

<CodeGroup>
```js
import { Sandbox } from '@e2b/code-interpreter'

// Create sandbox with metadata.
const sandbox = await Sandbox.create({
  metadata: {
    userId: '123', // $HighlightLine
  },
})

// List running sandboxes and access metadata.
const runningSandboxes = await Sandbox.list()
// Will print:
// {
//   'userId': '123',
// }
console.log(runningSandboxes[0].metadata)
```
```python
from e2b_code_interpreter import Sandbox

# Create sandbox with metadata.
sandbox = Sandbox(
  metadata={
    'userId': '123', # $HighlightLine
  },
)

# List running sandboxes and access metadata.
running_sandboxes = Sandbox.list()
# Will print:
# {
#   'userId': '123',
# }
print(running_sandboxes[0].metadata)
```
</CodeGroup>
