Adding HTML to Gutenberg - WordPress 5.0

A custom HTML block allows you to add HTML to Gutenberg and preview it as you edit.  Those who have used the classic editor should remember the 'text' tab.  This essentially recreates this as a block.

Step 1 - Hover your mouse over the Add Block icon (the plus sign in the upper left hand corner within the Gutenberg editor). Scroll to Formatting. Select Custom HTML.

Select the Custom HTML Block

Step 2 - The custom HTML block will appear. You’ll see a text editor that allows you to enter your code.

Paste HTML code in the HTML Block

This block can also be used if you have embed codes from certain services that aren't included in the "embed" block section.