WordPress

Installation

1. Upload the plugin through Plugins → Add New → Upload Plugin, or copy its folder into /wp-content/plugins/.
2. Activate CodeCogs Equation Editor under Plugins.
3. If your site uses the block editor, install and activate the official Classic Editor plugin, or add equations inside a Classic block. The fx button attaches to the Classic Editor's toolbar, which the block editor's own blocks do not have.
4. Give the plugin your licence key, below. Then open a post: the fx button is on the toolbar.

Your licence key

The plugin has no settings page; it reads its configuration from JavaScript globals set in the admin pages. The simplest place to set them is a small must-use plugin — a file in /wp-content/mu-plugins/:

<?php
// wp-content/mu-plugins/eqneditor-config.php
add_action( 'admin_head', function () {
    echo '<script>'
       . 'window.eqneditorServer  = "fxeditor.codecogs.com";'
       . 'window.eqneditorLicence = "fx_pk_your-key-here";'
       . '</script>';
} );Copy

Equations in your posts

The author chooses MathML or an SVG image in the dialog. The plugin lets MathML through WordPress's content filter, so Authors and Contributors can save it too — without that, WordPress strips <math> from the posts of anyone who cannot post unfiltered HTML.

For MathML to display at its best, your theme needs one stylesheet. Add it to the theme's header, or with wp_enqueue_style:

add_action( 'wp_enqueue_scripts', function () {
    wp_enqueue_style( 'fxtex', 'https://fxtex.codecogs.com/fxtex.css' );
} );Copy