Joomsef leaves a backlink on every single page of your Joomla site, if you are using the free version.
Here is how to remove this.
Open and edit this file relative to your Joomla site root: /components/com_sef/joomsef.php

Find line 2827 or search for $cachebuf2

cacheBuf = $doc->getBuffer('component');

       /* $cacheBuf2 = 
        '<div><a href="http://www.artio'.
        '.net" style="font-size: 8px; v'.
        'isibility: visible; display: i'.
        'nline;" title="Web development'.
        ', Joomla, CMS, CRM, Online sho'.
        'p software, databases">Joomla '.
        'SEF URLs by Artio</a></div>';*/

		// Fixing Yootheme and Joomla search
        if (JRequest::getCmd('format') != 'raw' &&  JRequest::getCmd('tmpl')!='raw')
        $doc->setBuffer($cacheBuf . $cacheBuf2, 'component');

Remove the $cachebuf2 content by commenting it out or simply delete it.

This solution might give you errors in the latest version Joomsef. So do this instead:

cacheBuf = $doc->getBuffer('component');
 
       /* $cacheBuf2 = 
        '<div><a href="http://www.artio'.
        '.net" style="font-size: 8px; v'.
        'isibility: visible; display: i'.
        'nline;" title="Web development'.
        ', Joomla, CMS, CRM, Online sho'.
        'p software, databases">Joomla '.
        'SEF URLs by Artio</a></div>';*/
        
         $cacheBuf2 ='';
 
        // Fixing Yootheme and Joomla search
        if (JRequest::getCmd('format') != 'raw' &&  JRequest::getCmd('tmpl')!='raw')
        $doc->setBuffer($cacheBuf . $cacheBuf2, 'component');