by Matt Cohen on WordPress.org
Scan a WordPress theme or plugin for functions that are attached to hooks and filters and for any custom actions or filters that are added by the code …

The WP Hook Finder main screen, before a scan.
WP Hook Finder is your assistant for developing on top of an advanced parent theme, theme framework or high-end WordPress plugin. Hook Finder scans a theme or plugin of your choice and lets you know of any custom actions or filters that have been added and which functions hook on to which actions or filters.