Philip Newcomer

This plugin makes all custom fields (post meta) visible in the “Custom Fields” meta box on post edit screens.

Show Hidden Post Meta

As a plugin developer, I create hidden post meta all the time and sometimes I need to see it to debug it. This does what it says it does, and well. Its simple and hasn't been updated for a while, but I'm glad it exists!

PS: If you need someone to take this one over, let me know. I'll keep it tested and updated if you're unable to.

Still works on 5.5

Makes hidden post meta visible on post edit screens

Themepure

The Pure Metafields Plugin is a powerful tool designed to enhance the functionality and flexibility of your WordPress website. With this plugin, you can easily create and manage custom meta boxes, adding extra fields and data to your posts, pages, and custom post types.
<h3>Key Features</h3>
✅ Custom Meta Boxes: Create unlimited custom meta boxes with ease. Define the title, placement, and priority of each meta box to suit your needs.
✅ Flexible Field Types: The plugin offers a wide range of field types to choose from, including text, textarea, select, checkbox, radio buttons, date picker, and more. Customize the field options and validation rules effortlessly.
✅ Repeatable Fields: Enable the ability to repeat fields, allowing users to add multiple instances of the same field dynamically. Perfect for scenarios where you need to capture multiple sets of data.
✅ Conditional Logic: Set up conditional logic to show or hide fields based on the value of other fields. This feature adds versatility and improves the user experience of your forms.
✅ Built-in Validation: Ensure data accuracy by implementing validation rules for your fields. You can define required fields, validate input formats, and customize error messages effortlessly.
✅ Save and Retrieve Meta Data: The plugin provides simple functions to save and retrieve meta data, allowing you to access and utilize the stored information in your themes or plugins.
✅ Integration with WordPress API: Seamlessly integrate with the WordPress API and extend its functionalities. Hook into actions and filters to manipulate meta data and create dynamic interactions.
<a href="https://themepure.net/plugins/puremetafields/" rel="nofollow ugc">Live Docs</a>

Pure Metafields

Very light weight playable plugin

Pure Metafields is very light weight plugin tused to create custom metabox for any post type like page, post and your custom post type support it.

Show Hidden Post Meta vs Pure Metafields