AJAX Chat Script is a Scripts software developed by blueimp.net. After our trial and test, the software is proved to be official, secure and free. Here is the official description for AJAX Chat Script:

Edit by Marydown: Ajax Chat is a free and fully customizable open source web chat software implemented in JavaScript, PHP and MySQL. Sound support is implemented using Flash, Socket support using Flash on client-side and Ruby on server-side.

Features
Easy installation
Usable as shoutbox
Multiple channels
Private messaging
Private channels
Invitation system
Kick offending Users
Ban offending Users
Ignoring offending Users
Online users list with user menu
Emoticons / Smilies
Easy way to add custom emoticons
BBCode support
Optional Flash based sound support
Optional visual update information (changing window title)
Clickable Hyperlinks
Splitting of long words to preserve chat layout
Flood control
Possibility to delete messages inside the chat
IRC style commands
Easy interface to add custom commands
Possibility to define opening hours for the chat
Possibility to enable/disable guest users
Persistent client-side settings
Multiple languages (auto-detection of ACCEPT_LANGUAGE browser setting)
Multiple styles
Chat window adjusts to browser window with included styles
Easy layout customization through stylesheets (CSS) and template system
Automatic adjustment of displayed time to local client timezone
Standards compliance (XHTML 1.0 strict)
Accepts any text input, including code and special characters
Multiline input field with the possibility to enter line breaks
Message lenght counter
Realtime monitoring and logs viewer
Support for unicode (UTF-8) and non-unicode content types
Bandwidth saving update calls (only updated data is sent)
Optional support to push updates over a Flash based socket connection (increased performance and responsiveness)
Survives connection timeouts
Easy integration into existing authentication systems
Sample phpBB2 integration provided
Sample phpBB3 integration provided
Sample MyBB integration provided
Sample PunBB integration provided
Sample SMF integration provided