Example switch for handling multiple websites with MODX.
In your /index.php: search & replace (+/- line 68)...
$modx->initialize('web');
...with this gist:
// $modx->initialize('web');
switch(strtolower(MODX_HTTP_HOST)) {
case 'www.example.com:80':
case 'www.example.com':
$modx->initialize('my-example-context'); // context for example.com
break;
case 'www.example2.com:80':
case 'www.example2.com':
$modx->initialize('my-example2-context'); // context for example2.com
break;
default:
$modx->initialize('web'); // default context
break;
}