WordPress Admin Search
I've been developing WordPress websites for a long time so I'm familiar with the WordPress admin interface, but I've never understood why I can't search everything on the website in one interface. You can search for posts within a post type, but only from that post type's admin page, it's not quick and it's not convenient.
I wanted something elegant like Spotlight on macOS – accessible from anywhere in the interface and simple to use. So I created a WordPress plugin that would do just that.