wpcocktail

The Site Title Caption Modifier is a simple WordPress plugin that sets the caption of all images in your WordPress site to the site title. This is particularly useful for maintaining a consistent branding or style across all posts and pages. The plugin works by hooking into the WordPress ‘img_caption_shortcode’ filter and modifying the caption output.

Image Caption for WP

Automatically sets the caption of all images to your site's title.

Marco Buttarini

Add IPTC credit to the caption of the image after have uploaded it.

Credit2Caption

Add IPTC credit to the caption of the image after have uploaded it.

Image Caption for WP vs Credit2Caption