Easy Add Thumbnail is a WordPress plugin designed to streamline the process of adding featured images to posts. With over 10,000 active installations, this free plugin automatically checks if a post has a featured image and assigns one if it does not. The plugin operates seamlessly without any setup required; simply install and activate it to enhance your content's visual appeal. It works effectively for various post types, including pages, and sets featured images dynamically for older posts when they are first viewed.

The plugin does not modify any existing data in your WordPress database and only adds the _thumbnail_id meta key to associate an image with a post. It requires at least one image to be attached to the post for functionality. Users can also exclude specific post types using filters as needed. However, the display and appearance of the featured images are entirely dependent on the active theme, ensuring flexibility in design.