Ryan

Easily add custom JavaScript or CSS to a single post or page.
When activated, a new icon is added to the post edit page near the icon you use 
to add media to a post. Clicking the new icon brings up a screen where you can 
insert JavaScript and CSS that will be included with the current post.
Anything entered into the text field on the JavaScript tab will be inserted into 
the <head> section of your web page. Same is true of the CSS tab. This allows 
you to insert arbitrary JavaScript and CSS into any post or page you would 
like without having to resort to loading it on all pages.

Insert JavaScript and CSS

Adds fields to the post and page edit pages that allow you to insert custom JavaScript or CSS for that post or page.

SilkyPress

Customize your WordPress site’s appearance by easily adding custom CSS and JS code without even having to modify your theme or plugin files. This is perfect for adding custom CSS tweaks to your site.
<h4>Features</h4>
<ul>
<li>Text editor with syntax highlighting </li>
<li>Print the code inline or included into an external file</li>
<li>Print the code in the header or the footer</li>
<li>Add CSS or JS to the frontend or the admin side</li>
<li>Add as many codes as you want</li>
<li>Keep your changes also when you change the theme</li>
</ul>

Simple Custom CSS and JS


When saving CSS as external file, I'm disappointed that you can't name the css file, you can change the permalink and then a duplicate CSS file is created with the name but it is still not used by this plugin.It is much better than Jetpack's version which is horrible.



I have now stopped using it as it also forces you to load the CSS where I needed to conditionally include it, I am now using a text editor, FTP, and wp_enqueue_style() in a child functions.php.  Much easier (at least after working it out), the below code added before the html header started (not sure if that matters):



//===========================================================================
function CompanyHeaderAssets()
//===========================================================================
{
    //--- Main Company CSS ------------------------------------------------
    $CssDir  = '/wp-content/themes/oceanwp-child-theme-master/';
    $CssName = 'Company CSS for Dynamic Pages.css';
    wp_enqueue_style("CompanyCss4All", "{$CssDir}{$CssName}", '', time());

    //--- Main Company CSS 4 ADMINS ---------------------------------------
    if  (IsCompanyVolunteer())
    {
        //--- Not displaying to visitors ------------------------------------
        $CssName = 'Company CSS for Image Gallery Metadata Tooltips (Volunteers Only).css';
        wp_enqueue_style("CompanyCss4StaffOnly4ImageMetadata", "{$CssDir}{$CssName}", '', time());
    }
}
add_action( 'wp_enqueue_scripts', 'CompanyHeaderAssets' );


Good Except Can't Name Files (4567.css etc)


This is a nice handy plugin, but it seems to not load CSS on Elementor pages for some reason. Otherwise nice plugin.


Handy plugin but...


This plugin does flush all permalinks settings on install, without confirmation of Admin, which impacted the whole permalinks settings, and required me to deactivate and reactivate multiple plugins to get their permalinks settings setup again, which is loss of time and requires a clear confirmation before doing that on install.


Impacted the permalinks

Just what I was looking for

Easily add Custom CSS or JS to your website with an awesome editor.

Insert JavaScript and CSS vs Simple Custom CSS and JS