2026 JUNE UPDATE FROM THE P4 TEAM: After initial investigation (see the comment on this idea for more details), we have determined that there is no way to reliably make sure that an image isn’t being used absolutely anywhere on the site. There is a risk that something in use in one part of the website not scanned by the tool might accidentally get deleted. We have declined the idea for this reason, but feel free to reach out to us if you think this type of implementation would be enough to comfortably let editors delete files with confidence.
In the spirit of cleaning up digitally, it would be useful to have a sort of tool that spots if an image isn’t being used anywhere on the site. Over time, so many images get uploaded and lost. If there was a tool to see that images aren’t being used anywhere, admins could remove them and making the site a bit more green.
Discussion
Based on this idea, I have experimented with a service called "Media Cleaner" that identifies unused media files in a WordPress website, to easily find and remove them. The service can be tested and checked here: https://github.com/greenpeace/planet4-master-theme/pull/2994 This implementation, in particular, only looks for media used as a featured image or as part of the Image block or the Cover block. Implementing a service like this is more complicated than it seems. Because WordPress has no centralized media usage registry, each system stores references differently, so all unused media must be searched for separately. Just to name a few, these are some of the places where media can be found: Featured image, Classic editor, Gutenberg blocks, ACF fields, Elementor, Divi, WooCommerce, Widgets, Nav menus, Site logo/favicon, Hardcoded in theme, etc. Furthermore, every new custom piece of code added by a plugin or a child theme introduces a new potential place where media files can be uploaded and found. There exists, however, a popular plugin used to identify and remove unused files: Media Cleaner. For testing and comparison, I installed it and used it on my local instance, and surprisingly, I got the same results as the custom solution of this PR. The problem with the plugin, nevertheless, is the same I mentioned before: media files are only analyzed in parts of the website already pre-established. There is no way to check for all of them globally.