Here is a nice list of WordPress plugins from Jeff Starr that are useful when developing or debugging. I’m happy to see BugFu at the top of the list as I’ve found it easy and useful.

For Block Theme Developers – Block themes come with two template part areas: header and footer. This tutorial by Justin Tadlock tells how to create additional template part areas for your theme, like a sidebar.

For Developers: This is a very cool video by Brian Coord showing how to add custom settings to an already existing block. The example shown walks-through adding some responsive block settings to do different visibility options at different sizes.

There is a new browser Popover API to standardize and simplify creating popovers without needing to use JavaScript. The first implementation will be coming soon to Chrome and Chrome-based browsers.

This is a tutorial for developers on adding patterns for the Query Loop block.

Interested in block development – this tutorial shows how to create a dynamic block using the RestAPI and the useEntityRecords to get a listof pages. It is a complete tutorial and you should be able to create a working block by following it.

Marcus Kober has written this in depth guide for developers on how to add hooks to your PHP code.

What happens behind the scenes when a WordPress page is loaded? This tutorial on the Learn WordPress site provides an overview of the page request lifecycle, from the query string to which template is used. The tutorial is high level enough for a power user to read, but has information useful for developers.