Klaylton Fernando

This plugin adds 3 fields on every page and blog post where you can type your code in a readable interface.
In addition to being very light and functional, the WP Custom Code plugin also allows you to work with external libraries. Basque paste the address 
of the javascript library of your choice in the designated field and you will be able to enjoy this indispensable resource.

WP Custom Code

Add CSS and Javascript to your pages simply and quickly. WP Custom Code supports CodeMirror.

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Intended users: Template Designers, Developer, Admins
If you wish to add any custom HTML to each page’s header, then this plugin is for you.
This is useful for verifying you are the owner of the website to services such as Mailchimp or Google. You can quickly add the verification codes to your page header without having to edit your site’s template.
In general, you can add custom CSS, a link to an external JavaScript file or something else. While it is generally recommended to create a child template if you’re going to make extensive, permanent changes to a template, there may be instances where a small change or two is needed that wouldn’t justify the creation of a child template—or your current template might not support child templates. You should nearly always avoid editing a template directly, because your changes will be lost when you next update the template.
This plugin is not affected by template changes.
<h3>Acknowledgements</h3>
Plugin Icon (CC BY 3.0) by <a href="https://www.iconfinder.com/denir" rel="nofollow ugc">DeniShop</a>

Add Code To Head

Add custom JavaScript/HTML/CSS codes to the page head without editing the template.

WP Custom Code vs Add Code To Head