AppNexus

aid: appnexus
name: AppNexus
description: AppNexus was a New York-based programmatic advertising technology company that ran one of the largest independent
  real-time online ad exchanges alongside a cloud-based buy-side and sell-side platform for advertisers, agencies, and publishers.
  AT&T acquired AppNexus in 2018 and rebranded it Xandr; Microsoft acquired Xandr in 2022 and productized it as Microsoft
  Monetize (sell-side) and Microsoft Invest (buy-side). Its developer surface lives on as the Digital Platform API (host api.appnexus.com)
  - a RESTful JSON API of roughly 150 services covering advertisers, insertion orders, line items, campaigns, creatives, publishers,
  sites, placements, deals and reporting - plus the actively released AppNexus mobile advertising SDKs for Android and iOS.
  Microsoft is discontinuing the Invest DSP effective 28 February 2026; the Monetize sell-side platform and the API remain
  live, documented on Microsoft Learn. No OpenAPI, MCP server or agent card is published, and API access is restricted to
  contracted customers. This profile was enriched by the API Evangelist pipeline from the public developer documentation.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - url: https://www.appnexus.com
    status: 301
    note: declared website redirects to https://about.ads.microsoft.com/en — a different registrable domain (appnexus.com
      -> microsoft.com), possible rename or acquisition (probed 2026-09-03, roadmap#169)
  generated: '2026-07-22'
  method: derived
image: https://raw.githubusercontent.com/api-evangelist/appnexus/refs/heads/main/apis.yml
url: https://raw.githubusercontent.com/api-evangelist/appnexus/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- first-round-capital
x-tier: stub
x-tier-reason: portfolio-lead
x-successor: xandr
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-08-12'
tags:
- Company
- AdTech
- Advertising
- Programmatic
- Ad Exchange
- DSP
- SSP
- Mobile SDK
- Marketing
tags_raw:
- Company
- Adtech
- Advertising
- Programmatic
- Ad Exchange
- DSP
- SSP
- Mobile SDK
- Marketing
apis:
- name: Digital Platform API
  description: RESTful JSON API for the AppNexus/Xandr programmatic advertising platform - manage advertisers, campaigns,
    line items, creatives, placements, inventory, deals, and pull reporting. Token authentication, offset pagination (start_element/num_elements),
    and a response/error envelope.
  humanURL: https://learn.microsoft.com/xandr/digital-platform-api/
  baseURL: https://api.appnexus.com
  tags:
  - Advertising
  - Programmatic
  - AdTech
  tags_raw:
  - Advertising
  - Programmatic
  - Adtech
  properties:
  - type: Documentation
    url: https://learn.microsoft.com/xandr/digital-platform-api/
  - type: APIReference
    url: https://learn.microsoft.com/en-us/xandr/digital-platform-api/reference
  - type: Authentication
    url: authentication/appnexus-authentication.yml
  - type: Conventions
    url: conventions/appnexus-conventions.yml
  - type: RateLimits
    url: rate-limits/appnexus-rate-limits.yml
  - type: DataModel
    url: data-model/appnexus-data-model.yml
  - type: ErrorCatalog
    url: errors/appnexus-error-codes.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://www.appnexus.com
- type: DeveloperPortal
  url: https://learn.microsoft.com/xandr/digital-platform-api/
- type: Documentation
  url: https://learn.microsoft.com/xandr/digital-platform-api/
- type: APIReference
  url: https://learn.microsoft.com/en-us/xandr/digital-platform-api/reference
- type: GettingStarted
  url: https://learn.microsoft.com/xandr/digital-platform-api/api-onboarding-process
- type: GitHubOrganization
  url: https://github.com/appnexus
- type: Authentication
  url: authentication/appnexus-authentication.yml
- type: Conventions
  url: conventions/appnexus-conventions.yml
- type: ErrorCatalog
  url: errors/appnexus-error-codes.yml
- type: Lifecycle
  url: lifecycle/appnexus-lifecycle.yml
- type: Deprecation
  url: https://learn.microsoft.com/en-us/xandr/digital-platform-api/breaking-changes
- type: StatusPage
  name: Xandr Status
  url: https://status.xandr.com
- type: ChangeLog
  name: Microsoft Monetize release notes
  url: https://learn.microsoft.com/en-us/xandr/monetize/release-notes
- type: ChangeLog
  name: Changelog surfaces (artifact)
  url: changelog/appnexus-changelog.yml
- type: Support
  name: Xandr Customer Support Portal
  url: https://help.xandr.com
- type: Login
  name: Microsoft Monetize console
  url: https://monetize.xandr.com/login
- type: Packages
  url: packages/appnexus-packages.yml
- type: SDKs
  name: anx-api (Digital Platform API JavaScript client)
  url: packages/appnexus-packages.yml
- type: SDKs
  name: AppNexus Android Mobile SDK
  url: packages/appnexus-packages.yml
- type: SDKs
  name: AppNexus iOS Mobile SDK
  url: packages/appnexus-packages.yml
- type: Components
  url: components/appnexus-components.yml
- type: RateLimits
  url: rate-limits/appnexus-rate-limits.yml
- type: Plans
  url: plans/appnexus-plans-pricing.yml
- type: DataModel
  url: data-model/appnexus-data-model.yml
- type: Conformance
  url: conformance/appnexus-conformance.yml
- type: Compliance
  name: Industry standards bodies Xandr states membership in (IAB Tech Lab, NAI, TAG, Prebid.org, W3C)
  url: conformance/appnexus-conformance.yml
- type: DomainSecurity
  url: security/appnexus-domain-security.yml
- type: VulnerabilityDisclosure
  url: security/appnexus-vulnerability-disclosure.yml
- type: Security
  name: Microsoft Security Response Center (parent-company disclosure channel for Xandr)
  url: security/appnexus-vulnerability-disclosure.yml
- type: LLMsTxt
  url: llms/appnexus-llms.txt
x-pointer-notes:
  withdrawn:
  - type: Sandbox
    reason: Withdrawn 2026-08-12. api-test.appnexus.com appears only inside a curl -v trace in the docs and 404s when probed;
      Xandr publishes no sandbox, test mode or test credentials. See sandbox/appnexus-sandbox.yml.
  not_emitted:
  - type: WellKnown
    reason: Every /.well-known path 404s on api.appnexus.com. www.appnexus.com and www.xandr.com 301 to about.ads.microsoft.com,
      whose SPA answers 200 with an HTML shell for every path - a soft-404, not a document. See well-known/appnexus-well-known.yml.
  - type: AgentCard
    reason: no agent-card.json or agent.json on any host; search-only artifact, nothing written.
  - type: CLI
    reason: anx-cli exists on npm but its only release is 0.1.10 from 2016-03-31 and the current documentation never mentions
      a CLI. Artifact kept at cli/appnexus-cli.yml as an abandonment record; no pointer emitted. See cli/appnexus-cli.yml.
  - type: Idempotency
    reason: no Idempotency-Key contract is documented anywhere in the Digital Platform API.
  - type:
    - OpenAPI
    - AsyncAPI
    - Webhooks
    - MCPServer
    - AgentSkill
    - OAuthScopes
    - Overlay
    - Protobuf
    reason: No machine-readable contract of any kind is published, and there is no event/webhook surface, MCP server or OAuth
      scope model to describe. Skills and overlays have no spec to ground them in.
  - type:
    - Pricing
    - TermsOfService
    - PrivacyPolicy
    reason: Explicitly not public - "The Xandr Service Policies, Privacy Regulations, Platform Terms of Service and Online
      Terms are confidential and tied to specific contracts between Xandr and its customers." See plans/appnexus-plans-pricing.yml.
x-enrichment:
  date: '2026-08-12'
  status: enriched
  artifacts_added: 8
  pass: local-v1