Mayo Moriyama

This is a plugin insert any HTML tag you like into footer area in whole website.
このプラグインは、何でもあなたのすきなHTMLタグを、サイト全体のページ末尾に表示させることができます。
<h3>English</h3>
<ol>
<li>Upload <code>navicast.php</code> to the <code>/wp-content/plugins/</code> directory.</li>
<li>Activate the plugin through the <code>Plugins</code> menu in WordPress.</li>
<li>Set your text through the <code>Option</code>><code>Reading</code> menu in WordPress.</li>
</ol>
<h3>日本語</h3>
<ol>
<li><code>navicast.php</code>を<code>/wp-content/plugins/</code>ディレクトリにアップロードします。</li>
<li>管理画面上の<code>プラグイン</code>から、プラグインを有効にします。</li>
<li>管理画面上の<code>設定</code>><code>表示設定</code>から、表示させるHTMLタグを設定し、保存します。</li>
</ol>

Mayuko Footer Tag Manager

This is a plugin insert any HTML tag you like into footer area in whole website.

SOGO

Tested with Gutenberg
Create a simple way to add javascript code to individual page post or custom post type header and footer, 
for example: add conversion code to thank you pages 
add google re-marketing code to individual pages 
and much more… 
added in version 1.3 the option to add script \ style to all pages not only individual pages, 
 this will allow you to add Google re-marketing code to the entire site or Google Analytics 
 to use it goto “settings” – “Header Footer Settings”
New Features (version 3.0): 
Added option for terms / category pages
New Features (version 2.3): 
 Added support for WooCommerce shop page.
<ol>
<li>
we support now exclude individual pages form printing the header and footer scripts, this is supported by 2 checkboxes in each page\post 
buy check it the script will not be display on this page
</li>
<li>
we added support to limit the script only for certain post type \ page
</li>
</ol>
if you like it \ use it – please rate us.
usage: 
You need to paste the code with the script tag, for example: 
 you js code

SOGO Add Script to Individual Pages Header Footer

Simple plugin to add script to header and footer for individual pages & posts

Mayuko Footer Tag Manager vs SOGO Add Script to Individual Pages Header Footer