CKEditor comes with a rich set of configuration options that make it possible to customize its appearance, features, and behavior. The main configuration file is named config.js. This file can be found in the root of the CKEditor installation folder (webapps/CommonsResources/ckeditor/config.js). By default, this file is mostly empty. To change the CKEditor configuration, add the settings that you want to modify to the config.js file.

For example:

CKEDITOR.editorConfig = function( config )
{
  config.language = 'en';
  config.uiColor = '#AADC6E';
};

Instead of using the default config.js file, you can create a copy of that file anywhere in your website and simply point the editor instances to load it. For example, in eXo Platform, the configuration file for CKEditor is placed at webapps/CommonsResources/eXoConfig.js, so the content of the config.js file will be:

CKEDITOR.editorConfig = function( config )
{
    config.customConfig = "../eXoConfig.js";
};