AppNexus

Brian O'Kelley (CEO)
Michael Rubenstein (President)
Jonathan Hsu (CFO)
Ryan Christensen (COO)

AppNexus is an American multinational technology company whose cloud-based software platform enables and optimizes programmatic online advertising. As of 2015, AppNexus servers process up to 45 billion ad buys per day at peak; AppNexus handled an estimated $2 billion in ad spending in 2014, giving it the biggest reach on the open web after Google. Headquartered in New York, the company has 23 offices in North America, Latin America, Europe, Asia and Australia.

AppNexus offers online auction infrastructure and technology for data management, optimization, financial clearing and support for directly negotiated advertising campaigns. It integrates with advertising sources including Google's DoubleClick, Microsoft's AdECN, engage:BDR and other aggregators. It operates out of multiple data centers, including one in Amsterdam serving Europe and the Middle East, in a facility shared with Equinix.

In 2016, AppNexus was ranked #21 on the Forbes Cloud 100 list.

AppNexus 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. The company is financially backed by Microsoft, Khosla Ventures, First Round Capital, Venrock, Kodiak Venture Partners, Marc Andreessen, Ben Horowitz, and Ron Conway; as of 2015 the company has raised $250 million in financing.