I tried to install the plugin and go the following error:
Plugin could not be activated because it triggered a fatal error. Parse error: syntax error, unexpected '&', expecting T_VARIABLE or '$' in /html/wp-content/plugins/wp-beautifier/beautifier.php on line 389
I looked at the line and basically what it's doing is appending to an array.
As of PHP 5, you can easily modify array's elements by preceding $value with &. This will assign reference instead of copying the value.
So the plugin is PHP5 dependant.
$ php -v PHP 4.4.8
My server doesn't have it so I cannot use the plugin.
Just a heads up!