AppNexus AppNexus is a global technology company whose cloud-based software platform enables and optimizes programmatic online advertising.ppNexus was founded by Brian O'Kelley (the ex-CTO of Right Media) and Mike Nolet (former product manager and Director of Analytics at Right Media); Michael Rubenstein, a former VP and General Manager at Google's DoubleClick, joined AppNexus as President in September 2009.