D O G S • 1.0 / 2.0 ( 2013 / 2014 ) • flf2ko, illeanore, yaohappy • web written in legacy PHP • judge written in Python, no judge queue • 3.0 ( 2014 ) • arbuztw, bigelephant29, shouko • architectural updates to enhance maintainability, security • enhanced state detection • 4.0 ( 2015 ) • forked from HOJ, deeply customized • 3.0 developers and many IM 106 students • web written in PHP with CodeIgniter • judge written in C#, with judge queue • 4s ( 2016 ) • project judge • minor enhancements