// Add referrer to hidden field in WP Forms function add_referrer_to_wpforms( $fields, $form_data ) { // Get referrer URL $referrer = wp_get_referer(); // Update hidden field value with referrer $fields['wpforms-175-field_16'] = $referrer; return $fields; } add_filter( 'wpforms_process_filter', 'add_referrer_to_wpforms', 10, 2 );