HTML Attributes Customizer for Blocks adds an HTML attributes panel in the block sidebar. Enter one attribute per line as name="value" (double quotes), or a boolean attribute as a single name (for example inert).
Attributes are stored on the block as JSON objects: htmlbacAttributes and htmlbacInnerAttributes (for example {"fetchpriority":"high","data-nolazy":"0"}). Boolean flags use true.
Merging: Duplicate names on multiple lines are combined. Values merge with spaces (semicolons for style). class merges with the block’s existing classes instead of replacing them.
Variables: Use tokens such as {{post.title}} or {{user.auth_status}} inside quoted values. They are replaced when the block renders on the front end.
Screenshots
Attributes tab — HTML attribute lines on a block (one per line: name="value" or boolean names).
Variables tab — Reference list of variables use inside quoted values.
Block editor — Image block selected with the HTML attributes panel open in the sidebar (Attributes and Variables tabs).