FCKeditor is an open source WYSIWYG text editor that can be used in web pages. It aims to be lightweight and requires no client-side installation.

Its core code is written in JavaScript, having server side interfaces with Active-FoxPro, ASP, ASP.NET, ColdFusion, Java, JavaScript, Lasso, Perl, PHP and Python.

For more information Click Here

Click here for FCKeditor Plugins Repository

Installing and adding plugin

Installing

To install a new plugin, copy the unzipped plugin to your editor’s plugin directory ‘editor/plugins’ (e.g. for the placeholder plugin the path to its fckplugin.js file would be ‘editor/plugins/placeholder/fckplugin.js’). That’s all!

Adding

You can then add the plugin in your custom Configuration File. You can either change the default path, and add it, or use the third paramter to FCKConfig.Plugins.Add to specify the path to the plugin:

// Change the default plugin path.
FCKConfig.PluginsPath = FCKConfig.BasePath.substr(0, FCKConfig.BasePath.length - 7) + '_samples/_plugins/' ;

// Add our plugin to the plugins list.
// FCKConfig.Plugins.Add( pluginName, availableLanguages )
// pluginName: The plugin name. The plugin directory must match this name.
// availableLanguages: a list of available language files for the plugin (separated by a comma).
FCKConfig.Plugins.Add( 'findreplace', 'en,it,fr' ) ;
FCKConfig.Plugins.Add( 'samples' ) 

// If you want to use plugins found on other directories, just use the third parameter.
var sOtherPluginPath = FCKConfig.BasePath.substr(0, FCKConfig.BasePath.length - 7) + 'editor/plugins/' ;
FCKConfig.Plugins.Add( 'placeholder', 'en,it,de,fr', sOtherPluginPath ) ;
FCKConfig.Plugins.Add( 'tablecommands', null, sOtherPluginPath ) ;
FCKConfig.Plugins.Add( 'simplecommands', null, sOtherPluginPath ) ;

Some Useful FCKeditor Plugins you can download from here.