Officially supports Magento 2.2.0+
composer require nathanjosiah/magento2-layout-debugger:dev-master
Register it with Magento
For production mode also run
bin/magento setup:di:compile bin/magento setup:static-content:deploy
Go to Store->Configuration->Advanced->Developer->Debug
Outputs a popup containing information about the rendered layout for a given page. The popup can be expanded and hidden.
Will add unobtrusive comments as to not interfere with CSS selectors and rendered HTML that help you quickly see where HTML is coming from in the layout.
This will be the name of the layout element, the type of the element (block, container, ui component), and the name of the parent element