Plugin Directory

Developer's Custom Fields

Provides developers with powerful and flexible tools for managing post and user custom fields.

This plugin is aimed at plugin and theme developers who want a set of tools that allows them to easily and flexibly define custom fields for all post types, and for user profiles.

Full documentation at http://sltaylor.co.uk/wordpress/plugins/slt-custom-fields/docs/.

Code on GitHub.

Issue tracking on GitHub. If you're not sure if you've found a genuine issue or not, please start a thread on the WP forum.

Please note that this plugin isn't suitable for non-developers. It has been intentionally designed without a user interface for defining fields, and some aspects may be "unfriendly" to anyone not comfortable with hands-on WordPress development.

Here are some similar plugins with interfaces for defining fields.

Also, if you're a developer and this plugin doesn't quite fit your requirements, one of these might:

Please note that I haven't tested these, and can't vouch for their quality.