Convert ACF php files to ACFJSON

acfphp2json.php

<?php

function convert_ACF_PHP_2_Json() {
  $status = [];

  $theme_dir = get_stylesheet_directory();
  $json_output_dir = $theme_dir . '/acf-json/';

  if (!file_exists($json_output_dir)) {
    die('Create a acf-json/ directory in your current theme.');
  }

  $fieldgroups = glob($theme_dir . '/field-groups/*');

  foreach ( $fieldgroups as $fg ) {
    $field = $fg . '/data.php';

    if ( file_exists($field) ) {
      // Include $field into current context
      // this will create a $group var
      include($field);
      if (file_put_contents($json_output_dir . $group['id'] .'.json', json_encode($group) )) {
        $status[] = 'Created json file ' . $group['id'] . ' for ' . $group['title'] . '.';
      }
    }
  }

  if (count($status)) {
    echo implode("<br/>", $status);
  } else {
    echo 'No ACFJson files created.';
  }

  die();
}

convert_ACF_PHP_2_Json();

Paste this function into your theme and it will convert field groups to JSON. Assumes that your field groups are structured as:

field-groups/
  field/
    data.php
  field2/
    data.php
  …

Uses a die() so will break your site.