Joost de Valk

Yoast

Allows you to easily find the custom fields (including hidden custom fields) and their values for a post, page or custom 
post type post.
Just go to Tools – Custom field finder, enter the post ID of any post and you’ll see all the custom fields. This includes 
the custom fields that start with an underscore ( _ ) that are normally hidden from the custom fields interface.

Custom field finder

Allows you to easily find the custom fields (including hidden custom fields) and their values for a post, page or custom post type post.

marapper

Manage custom fields using the insert shortcodes [custom name=”field-name” value=”field-value“] or HTML conditional comments <!–custom name=”field-name” value=”field-value“–> in text of post. It’s a hook for desktop blog clients, which don’t support customfields natively.
Простой хак Вордпресса, позволяющий управлять произвольными полями из любого внешнего клиента или при отправке через почту с помощью шорткодов [custom name=”имя-произвольного-поля” value=”значение“] или условных комментариев <!–custom name=”имя-произвольного-поля” value=”значение“–> прямо в тексте поста.

Custom Shortcodes

Manage custom fields using the insert shortcodes or HTML comment in text of post.

Custom field finder vs Custom Shortcodes