4.42.0 • Public • Published


GScan is a tool for validating Ghost themes. It produces detailed reports of issues where themes need to be modified in order to be compatible with a specific version.

It is actively capable of dealing with the current and last major versions of Ghost (so at the time of writing v4, v3, v2 and v1).

GScan works on a system of rules. Each rule has a way to check whether it passes or fails and has help content which describes how to fix it. Each rule is also marked with an error level:

  • recommendation = these are things the dev might want to know about
  • warning = usually used for deprecations, things that will be errors in the next version
  • error = anything that makes the theme invalid or incompatible with the current version of Ghost

In addition, an error can be marked as fatal. A fatal error means, left unchecked a Ghost publication would throw 500 errors on certain pages because of the detected out-of-date or erroneous code.

In Ghost, we call GScan on boot. If any fatal errors are detected in Ghost(Pro) and in Ghost-CLI we call GScan as part of major upgrades. The upgrade will not be allowed to continue if any fatal errors are detected.

Errors are only marked as fatal errors if they would cause errors, and therefore should block a boot or an upgrade.


When developing new rules or testing gscan following tools are great to have in the toolbelt:

  • astexplorer - absolutely awesome Handlebars AST fiddler, helpful when testing out new ideas and exploring what's possible through AST parser;


There are 3 ways to use gscan to validate your theme:

1. Web usage

Visit and upload your zip to our online version of Gscan.

2. CLI usage

Install using yarn / npm:

yarn global add gscan / npm install -g gscan

To run a local directory through the checks:

gscan /path/to/theme/directory

To run a local zip file through the checks:

gscan /path/to/ -z

By default, GScan scans themes for the latest Ghost version compatibility. You can also specify a Ghost version by using the following parameters (for Ghost 1.0, 2.0, 3.0, 4.0 and 5.0):

--v1 or -1
--v2 or -2
--v3 or -3
--v4 or -4 or --canary --v5 or -5

Use the --canary parameter to check for the upcoming Ghost version.


gscan /path/to/ -z1 - scan a theme in a zip file for Ghost 1.0 compatibility
gscan /path/to/theme/directory --v2 - can a theme in a directory for Ghost 2.0 compatibility
gscan /path/to/theme/directory --canary - scan a theme for the upcoming version of Ghost

3. Lib usage

Install using yarn/npm and then:

var gscan = require('gscan');

    path: 'path-to-zip',
    // if you need to check the theme for a different
    // major Ghost version, you can pass it. Currently
    // v1, v2, v3, v4 and canary (v5) are supported. Default is
    // the latest Ghost version 4.0:
    // checkVersion: 'v4',
    name: 'my-theme'
}).then(function (result) {
}).catch(function(err) {




(Core team only)

  • yarn ship

Result types:

  • Errors: these are issues which will cause your theme to not work properly. These must be fixed.
  • Warnings: these are usually related to deprecated features. These should be fixed.
  • Recommendations: these are advisories about best practice. Fixing these will improve your theme.
  • Features: detected features which may impact on compatibility. Nothing to do :)

Still To Do:

  • Support for running the checks against a GitHub repository
  • Many, many more checks
  • Detailed advice for each check/result
  • Compatibility report
  • Feature listing

Copyright & License

Copyright (c) 2013-2023 Ghost Foundation - Released under the MIT license. Ghost and the Ghost Logo are trademarks of Ghost Foundation Ltd. Please see our trademark policy for info on acceptable usage.

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