Build API class JSON for my joomla APP

I want to create or modify this API attached ([login to view URL]) (JSON) so that it works for PHP version 5.3 to 7.x (up to date and new php versions). If I am using php 5.x it works well but does not work for php 7 and on some PHP environment. I also want something better as in the second attached file ([login to view URL])