# Environment Variables

xlwings Lite runs in the secure sandbox of a browser and therefore can’t access anything on your local computer. This means that it also can’t access local environment variables such as `USERPROFILE`, etc.

However, you can set environment variables with two different scopes:

- **Local scope**: stored in the browser’s local storage and available across all workbooks. However, they will be deleted when you clear the Office cache, so make a backup!

  #### WARNING
  **Security Warning:** When using environment variables with scope “Local”, only open trusted workbooks from known sources. Malicious workbooks could otherwise exfiltrate these variables.
- **Workbook scope**: stored in the current workbook.

**Note:** Local scope overrides Workbook scope.

To set an environment variable:

- Provide the `Name`, `Value`, and `Scope` and hit `Save`.
- Restart xlwings Lite

For example, if you set the following environment variable:

- Name: `OPENAI_API_KEY`
- Value: `your-key`

You can access them like this in your code:

```python
import os
import xlwings as xw
from xlwings import func, script

@script
def sample_script(book: xw.Book):
    key = os.getenv("OPENAI_API_KEY")
    if key is not None:
        print(key)
    else:
        raise Exception("Store your OPENAI_API_KEY key under Environment Variables!")
```