> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ghost.org/llms.txt
> Use this file to discover all available pages before exploring further.

# GScan

> Validating your Ghost theme is handled efficiently with the GScan tool. GScan will check your theme for errors, deprecations and compatibility issues. GScan is used in several ways:

***

* The [GScan site](https://gscan.ghost.org) is your first port of call to test any themes that you’re building to get a full validation report
* When a theme is uploaded in Ghost admin, it will automatically be checked with `gscan` and any fatal errors will prevent the theme from being used
* `gscan` is also used as a command line tool

### Command line

To use GScan as a command line tool, globally install the `gscan` npm package:

```bash theme={"dark"}
# Install the npm package
npm install -g gscan

# Use gscan <file path> anywhere to run gscan against a folder
gscan /path/to/ghost/content/themes/casper

# Run gscan on a zip file
gscan -z /path/to/download/theme.zip
```