Plugins

You have 3 options for installing plugins:

1. In your site source root, make a _plugins directory. Place your plugins here. Any file ending in *.rb inside this directory will be loaded before Jekyll generates your site.

2. In your _config.yml file, add a new array with the key plugins (or gems for Jekyll < 3.5.0) and the values of the gem names of the plugins you’d like to use. An example:

   # This will require each of these plugins automatically.
   plugins:
     - jekyll-gist
     - jekyll-coffeescript
     - jekyll-assets
     - another-jekyll-plugin
   

   Then install your plugins using gem install jekyll-gist jekyll-coffeescript jekyll-assets another-jekyll-plugin

3. Add the relevant plugins to a Bundler group in your Gemfile. An example:

   group :jekyll_plugins do
     gem "jekyll-gist"
     gem "jekyll-coffeescript"
     gem "jekyll-assets"
     gem "another-jekyll-plugin"
   end
   

   Now you need to install all plugins from your Bundler group by running single command bundle install.

Plugins on GitHub Pages

GitHub Pages is powered by Jekyll. All Pages sites are generated using the --safe option to disable plugins (with the exception of some whitelisted plugins) for security reasons. Unfortunately, this means your plugins won’t work if you’re deploying to GitHub Pages.
You can still use GitHub Pages to publish your site, but you’ll need to convert the site locally and push the generated static files to your GitHub repository instead of the Jekyll source files.

_plugins, _config.yml and Gemfile can be used simultaneously

You may use any of the aforementioned plugin options simultaneously in the same site if you so choose. Use of one does not restrict the use of the others.

The jekyll_plugins group

Jekyll gives this particular group of gems in your Gemfile a different treatment. Any gem included in this group is loaded before Jekyll starts processing the rest of your source directory.

A gem included here will be activated even if its not explicitly listed under the plugins: key in your site’s config file.

Gems included in the :jekyll-plugins group are activated regardless of the --safe mode setting. Be aware of which gems are included under this group!