WPForms: new smart tag – Current Unix Time

// Register the smart tag.

add_filter( 'wpforms_smart_tags', static function( $tags ) {

	// Key is the tag, value is the tag name.

	$tags['current_unix_time'] = 'Current Unix Time';

	return $tags;

} );

// Replace its value on form render on front-end.

add_filter( 'wpforms_process_smart_tags', static function( $field_val, $form_data ) {

	return str_replace( '{current_unix_time}', wp_date( 'U' ), $field_val );

}, 10, 2 );