Phoenix Online

This easy-to-use plugin allows you to quickly and easily edit post meta values for almost any post type (including custom post types)
Edit post meta as plain text, in textareas, as light-weight HTML or using the full WordPress WYSIWYG editor!
From the first version, this has been designed for ease of use by site Contributors and Editors, but keeps settings reserved for Admin’s only. This gives site Adaministrators control over what less-privileged users can bulk edit.

Bulk Postmeta Editor

This plugin makes it easy to check and edit serialized data in a targeted and comfortable way. Both custom fields and hidden meta data can be easily queried by post type. The plugin then lists all data in an editable input field of your choice which makes comparing and editing the data a breeze.  


Very helpful for debugging

Allows you to bulk-edit post meta information (including custom post types) from a single place.

Andrew Norcross

tripflex

Creates a panel to change or delete meta keys in bulk. Useful for when you are switching plugins or themes that use specific meta keys for functionality, or for general cleanup for older sites that may have older meta data that is no longer in use.

Post Meta Manager

A simple utility plugin for changing or deleting post or user meta (custom fields) keys in bulk.

Bulk Postmeta Editor vs Post Meta Manager