Y.Kohno

This is a flexible search form widget. 
You can easily generate a multi condition search form and display anywhere as widget.
複数のカスタムフィールド、投稿タイプ、カテゴリー、タグでの検索が可能な複合検索フォームを簡単作成できるプラグイン。ウィジェットで好きな場所に設置可能。
Currently supports 
– Custom Fields 
– Taxonomies 
– Categories 
– Post tags 
– Post Type

WP Meta Search

Search form for searching through custom fields, post types, categories, tags, and free text.

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.

WP Meta Search vs Bulk Postmeta Editor