wpler

<p><a href="https://www.wpler.com/linkmanager-fur-multisites/" rel="nofollow ugc">Deutsche Beschreibung des Plugins</a></p>
<p>You run a Multisite Blogsystem with open registration for users to add own blogs and their can using a theme by<br />
different installed themes, but you want to show a link into the footers of the themes but only once time and for<br />
every blog another one?</p>
<p>With this plugin you can manage your outgoing links into the themes by a shortcode/function for every blog. You can<br />
set for every link the target, relation (Attribute rel), linktext and -title and the target url. Also you can set more<br />
than one link for a blog.</p>
<p>For output you can use a shortcode or a function . This function get the links<br />
for the current blog-id and printed this, if links are available.</p>
<p>All options/links can set by network admin only. The outputs needs no capability.</p>


WPMU LinkManager

Manage your Themes footer links for every blog into a multisite includes with conditional tags.

Anand Kumar

Digital Liberation

<p>If you are running a WordPress site then sooner or later you need to insert some kind of code to your website. It is most likley a web analytics code like Google Analytics or may be social media script or some CSS stylesheet or may be Custom fonts. This plugin will do all the magic. Even if you want to insert those codes in a custom post type.</p>
<p>All you have to do is adding appropriate html code.</p>
<p>Don’t forget to wrap your code with proper tags.</p>
<pre><code><script type="text/javascript">
YOUR JS CODE HERE
</script>
</code></pre>
<p>Or for CSS:</p>
<pre><code><style type="text/css">
YOUR CSS CODE HERE
</style>
</code></pre>
<h4>Why use this plugin:</h4>
<ul>
<li>To insert CSS and JavaScript codes to <code><head></code> or before <code></body></code>.</li>
<li>To insert code to <code><head></code> of any single page or post.</li>
<li>To insert code to Custom Post Type [New Feature].</li>
</ul>
<p>The plugin should be compatible with WooCommerce.</p>
<h4>What it does not offer</h4>
<ul>
<li>You can’t insert/execute PHP codes.</li>
</ul>
<p>Almost all WordPress theme do support this “Header and Footer Scripts” plugin. If the codes are not appearing in your site [ask for support] or look at your theme file if they have standard <code>wp_head</code> and <code>wp_footer</code> hooks.</p>
<h4>Important Links</h4>
<p>For furhter information you are welcomed to follow these links:</p>
<ul>
<li><strong><a href="https://github.com/anandkumar/header-and-footer-scripts/wiki" rel="nofollow ugc">Read Documentation</a></strong></li>
<li><strong><a href="https://wordpress.org/support/plugin/header-and-footer-scripts/" rel="ugc">Get Support</a></strong></li>
<li><strong><a href="https://github.com/anandkumar/header-and-footer-scripts" rel="nofollow ugc">GitHub Repository</a></strong></li>
</ul>


Header and Footer Scripts

good

Como es posible que al desinstalar el plugin, si no has borrado el script te deje el código ahi metido. Y luego a averiguar de donde vienen los errores. 

Al desinstalar te deja el código

Header and Footer Scripts plugin allows you to add scripts to WordPress site's  and just before closing  tag.

WPMU LinkManager vs Header and Footer Scripts