Moving from ACF

WP Freeform Fields reads values where ACF saved them and keeps field keys, so a site can move over without converting data.

Steps

1. Back up the site.
2. Install and activate WP Freeform Fields next to ACF. While ACF is active, WP Freeform Fields stays out of its way: ACF's fields, acf-json files, blocks and function names remain ACF's.
3. Open Custom Fields → Tools → Migrate from ACF. Read the theme check first: it lists any ACF functions or acf/… hooks your theme uses that WP Freeform Fields does not provide. Then import.
4. Deactivate ACF. Themes that use get_field() keep working: values are read where ACF saved them, and acf/… filters in the theme (for example acf/load_field that fills choices) keep running.

With WP-CLI, step 3 is:

wp wpff import-acf --dry-run
wp wpff import-acf

The import moves post types, taxonomies, options pages and field groups from the database, in that order.

If ACF is deactivated first

The site keeps working: field groups and options pages are read from ACF's tables (read-only, marked ACF in the list) until you migrate them.

ACF JSON files in acf-json are read too. Groups exported from ACF as PHP work as they are.

ACF to REST API

The REST output of the ACF to REST API plugin (acf/v3/… routes and the acf property) is served too while that plugin is active and ACF is not, with stricter access:

• only the fields of each object's groups;
• core REST visibility rules;
• options page fields only for users who may open the page, unless the group is shown in REST.

Before switching a production site

Read Known differences and ACF compatibility.