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Brief
AppNexus was rebranded to Xandr (Sep 2018) and acquired by Microsoft (Dec 2021) (see deal), then rebranded to Microsoft Advertising— see Microsoft for current status.— See the full lineage →
AppNexus

AppNexus

Programmatic Advertising Technologyappnexus.com

AppNexus was an American multinational technology company that operated a cloud-based software platform enabling and optimizing programmatic online advertising, founded in 2007 by former Right Media staff, CTO Brian O'Kelley, and Mike Nolet.

Last updated Oct 22, 2026 by the ATDb Editorial Team · Connections updated Oct 26, 2026

In the news
Founded
2007
HQ
New York, New York, United States
Connections
81

AI-drafted from public sources32 sources cited

At a glance

Employees
1001-5000
Funding
~$290M
Revenue
$300M–$500M (est. pre-acquisition)
51integrations12competitors
Demand Side Platform (DSP)Supply Side Platform (SSP)Programmatic Platform

About

One of the largest independent programmatic advertising platforms prior to acquisition, competing directly with Google DoubleClick as a full-stack buy-side and sell-side ad tech provider

AppNexus was an American multinational technology company that operated a cloud-based software platform enabling and optimizing programmatic online advertising, founded in 2007 by former Right Media staff, CTO Brian O'Kelley, and Mike Nolet. In June 2018, AT&T acquired AppNexus and placed it under its Xandr division, with the deal reportedly valued at $1.6 billion. Microsoft subsequently acquired Xandr in 2022 and folded it into its advertising business, productizing it as Microsoft Monetize on the sell side and Microsoft Invest on the buy side. Source 1: wikipedia.org — AppNexus Source 2: apis.io — AppNexus — API Provider, Schemas

Business model

SaaS / Marketplace

Target market

Enterprise

What they offer

  • AppNexus Marketplace

    Open programmatic marketplace connecting buyers and sellers of digital advertising inventory through real-time bidding

  • Seller Platform (SSP)

    Supply-side platform enabling publishers to manage, sell, and optimize their ad inventory programmatically

  • Buyer Platform (DSP)

    Demand-side platform enabling advertisers and agencies to purchase digital media across exchanges and inventory sources

  • Publisher Ad Server

    Ad serving technology for publishers to manage direct-sold and programmatic campaigns across their properties

  • AppNexus Console

    Unified UI for managing programmatic buying and selling campaigns, reporting, and optimization

Key features

Real-time bidding (RTB) infrastructureFull-stack buy-side and sell-side platformOpen and customizable programmatic marketplaceAdvanced audience targeting and segmentationCross-channel inventory support (display, video, mobile, native)Robust reporting and analyticsPublisher yield management toolsAPI-first architecture for custom integrations

Use cases

Programmatic display and video advertising buyingPublisher inventory monetizationPrivate marketplace (PMP) deal executionReal-time audience targeting and retargetingAd network and trading desk infrastructureCross-exchange media buying for agencies

Customer segments

Digital publishers and media ownersAdvertising agencies and trading desksAd networksDemand-side platformsBrand advertisers

Tech & specs

Technology stack

Cloud-based distributed infrastructureReal-time bidding (RTB) protocolRESTful APIsBig data analytics and reporting pipelinesMachine learning for bid optimization

Security & compliance

GDPRCCPAIAB standards compliance

Deployment

Cloud

API

Yes

Corporate history
  1. 2007 · Founded
  2. 2018Became Xandr3 sources
  3. 2021Acquired by Microsoft3 sources
  4. Year unknown
Connection details
See alternatives to AppNexus See integrations with AppNexus (51)

Explore further

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On the AtlasDemand-Side PlatformsOn the Mapby country + regionOn the GraphNetwork around AppNexus