DEV3 AI Field Filler for ACF

WordPress plugin for Advanced Custom Fields and Secure Custom Fields: it fills a post's custom fields from its content with the Google Gemini API, using a schema built from each field's settings, then checks every value with its own codec and ACF's validation before saving. Free download: sign in and click Download ZIP. Add your own Google AI Studio (Gemini) API key to switch on the AI features; the documentation says which features work without one.

How it works

We built DEV3 AI Field Filler for ACF as a PHP plugin with a React admin app and buttons inside ACF's own meta boxes in the block and classic editors. A codec sits between ACF and the AI in both directions.

Key design decisions

• A schema per field. Each ACF field becomes part of a structured-output schema: maxLength from the character limit, minimum and maximum for numbers, an enum of choice values, objects for links and groups, arrays of rows for repeaters and a layout enum for flexible content.
• Real candidates only. Relationship, post object, taxonomy, user, image and gallery fields get a list of real candidates built from the field's own filters, and the schema only allows those ids. Fields with no candidates aren't asked at all.
• Normalise, then validate twice. Every returned value goes through a type-aware normaliser (clamp and step-round numbers, map choice labels to values, parse dates into ACF's storage formats, re-check post type and status) and then through ACF's own acf_validate_value(), including any custom acf/validate_value filters.
• Explain every change. When the codec shortens text, clamps a number or drops an invalid choice, it adds a note. Invalid values are flagged and can't be applied until edited.
• Per-field instructions in ACF. A DEV3 AI tab in ACF's field settings stores instructions and a skip switch on the field itself, so they travel with local JSON and exports.
• History and undo. Every applied value records before and after, including whether the field existed, so undo can restore or delete.

Architecture

In the editor, "Fill with DEV3 AI" works per field or per field group and opens a review modal with current and proposed values; accepted values go into the ACF form and are saved with the post. Bulk fill drafts values for many posts in a background job into a review queue with accept-all and batch undo. The field-group generator turns a plain description into a reviewed field group, created in the database or as a local JSON file. A basic mode fills fields without AI from the post's own content. The API client and jobs come from a shared core used across DEV3's plugins.

What's in the download

• The installable plugin zip: upload it through Plugins → Add New → Upload Plugin.
• Full HTML documentation (installation, settings, hooks, FAQ).

Requirements

• WordPress 6.0 or newer and PHP 7.4 or newer
• Advanced Custom Fields 6.0 or newer (free or Pro) or Secure Custom Fields, active
• Repeater, flexible content and gallery fields need ACF Pro or Secure Custom Fields
• Optional: a Google Gemini API key. Without one, basic fill, field-group templates, the review queue, history and undo still work

Learn more

• How we built it: the AI Field Filler case study
• Engineering write-up on the DEV3 blog
• Also free in the DEV3 AI Content, SEO & Site Tools Plugins Bundle with every other Content, SEO & Site Tools plugin.