# AppNexus (Xandr / Microsoft Monetize)

> AppNexus was a New York programmatic advertising company running a real-time ad exchange plus a
> cloud buy-side and sell-side platform. AT&T acquired it in 2018 and rebranded it Xandr; Microsoft
> acquired Xandr in 2022 and productized it as Microsoft Monetize (sell-side) and Microsoft Invest
> (buy-side). The developer surface survives as the Digital Platform API on host api.appnexus.com,
> documented on Microsoft Learn, plus the actively released AppNexus mobile advertising SDKs.
> Microsoft is discontinuing the Invest DSP effective 2026-02-28; the Monetize sell-side platform
> and the API remain live. This file was generated by the API Evangelist enrichment pipeline from
> public documentation on 2026-08-12. No OpenAPI is published.

## API
- [Digital Platform API](https://learn.microsoft.com/en-us/xandr/digital-platform-api/): RESTful JSON API covering ~150 services for buy-side and sell-side ad operations, reporting, and platform management. Base URL https://api.appnexus.com. Access requires an active customer account; there is no sandbox and no self-serve sign-up.

## Docs
- [Digital Platform API overview](https://learn.microsoft.com/en-us/xandr/digital-platform-api/)
- [API Reference index (all services)](https://learn.microsoft.com/en-us/xandr/digital-platform-api/reference)
- [Getting Started](https://learn.microsoft.com/en-us/xandr/digital-platform-api/api-getting-started)
- [API Onboarding Process](https://learn.microsoft.com/en-us/xandr/digital-platform-api/api-onboarding-process)
- [API Semantics (REST conventions, filtering, paging, errors)](https://learn.microsoft.com/en-us/xandr/digital-platform-api/api-semantics)
- [API Best Practices](https://learn.microsoft.com/en-us/xandr/digital-platform-api/api-best-practices)
- [API Usage Constraints (rate limits, object limits, pagination)](https://learn.microsoft.com/en-us/xandr/digital-platform-api/api-usage-constraints)
- [Authentication Service](https://learn.microsoft.com/en-us/xandr/digital-platform-api/authentication-service)
- [Token-based (JWT) API Authentication](https://learn.microsoft.com/en-us/xandr/digital-platform-api/token-based-api-authentication)
- [Breaking Changes policy](https://learn.microsoft.com/en-us/xandr/digital-platform-api/breaking-changes)
- [API Support](https://learn.microsoft.com/en-us/xandr/digital-platform-api/xandr-api-support)
- [Mobile SDK documentation](https://learn.microsoft.com/en-us/xandr/mobile-sdk/)
- [Policies and Regulations](https://learn.microsoft.com/en-us/xandr/policies-regulations/)

## Operations
- [Status page (Atlassian Statuspage)](https://status.xandr.com)
- [Status API](https://status.xandr.com/api/v2/summary.json)
- [Microsoft Monetize release notes](https://learn.microsoft.com/en-us/xandr/monetize/release-notes)
- [Microsoft Invest release notes (dormant since 2025-09-23)](https://learn.microsoft.com/en-us/xandr/invest/release-notes)
- [Android SDK release notes](https://learn.microsoft.com/en-us/xandr/mobile-sdk/android-sdk-release-notes)
- [iOS SDK release notes](https://learn.microsoft.com/en-us/xandr/mobile-sdk/ios-sdk-release-notes)
- [Customer Support Portal](https://help.xandr.com)

## SDKs
- [anx-api (npm, v8.2.1, 2025-11-10)](https://www.npmjs.com/package/anx-api): the only maintained Digital Platform API client library.
- [Android Mobile SDK (Maven Central com.appnexus.opensdk:appnexus-sdk, v9.13.0, 2026-06-10)](https://central.sonatype.com/artifact/com.appnexus.opensdk/appnexus-sdk)
- [iOS Mobile SDK (Swift Package Manager, v9.13.0, 2026-06-10)](https://github.com/appnexus/mobile-sdk-ios-spm)
- [iOS Mobile SDK (CocoaPods AppNexusSDK, v9.9.1, 2025-11-13 - four minors behind SPM)](https://cocoapods.org/pods/AppNexusSDK)
- No Python, Java, Go, Ruby, PHP or .NET client exists for the Digital Platform API. Every documented example is raw curl.

## Conventions
- Authentication: POST /auth with {auth:{username,password}} returns a session token; carry it in an `Authorization` header or a cookie. 2h idle / 24h hard expiry. Max 10 successful auths per 5 minutes - re-authenticate only after seeing `error_id: NOAUTH`.
- Pagination: `start_element` / `num_elements`, capped at 100 objects per GET response; `count` on every response gives the total.
- Filtering: `?id=1,2,3`, `?field=value`, range prefixes (`min_`, `max_`, `not_`, `like_`, `having_`), `?fields=a,b,c` projection, `?sort=id.desc`, dates as `YYYY-MM-DD+HH:MM:SS` UTC.
- Array writes: PUT overwrites an entire array unless `?append=true`.
- Response envelope: `{"response": {"status": "OK", "count": N, "dbg_info": {...}}}`. Errors carry `error_id` (machine token) and `error` (prose) inside the same envelope - parse `error_id`, do not branch on HTTP status alone.
- Rate limiting: 429 for the user-level limit, 503 for the service-level limit; both carry `x-ratelimit-code` and `Retry-After`. No published numeric limit. Not RFC 9457, not the IETF RateLimit headers.
- Idempotency: not supported. No Idempotency-Key contract exists.
- Versioning: URI path (`/` or `/current/`, pinned as `/v1.16/`). Breaking changes run two parallel versions for 60 days and are announced by email, not by a Sunset header.

## Repo artifacts
- [Authentication profile](authentication/appnexus-authentication.yml)
- [API conventions](conventions/appnexus-conventions.yml)
- [Error codes](errors/appnexus-error-codes.yml)
- [Rate limits and object limits](rate-limits/appnexus-rate-limits.yml)
- [Data model / entity graph](data-model/appnexus-data-model.yml)
- [Conformance and industry standards](conformance/appnexus-conformance.yml)
- [Lifecycle, deprecation, status page](lifecycle/appnexus-lifecycle.yml)
- [Changelog surfaces](changelog/appnexus-changelog.yml)
- [Packages / SDKs](packages/appnexus-packages.yml)
- [CLI (abandoned)](cli/appnexus-cli.yml)
- [Client components](components/appnexus-components.yml)
- [Plans and pricing (none published)](plans/appnexus-plans-pricing.yml)
- [Sandbox (none published)](sandbox/appnexus-sandbox.yml)
- [Well-known probe (all miss)](well-known/appnexus-well-known.yml)
- [Domain security](security/appnexus-domain-security.yml)
- [Vulnerability disclosure](security/appnexus-vulnerability-disclosure.yml)

## Not published
- No OpenAPI, Swagger, GraphQL, AsyncAPI or Protobuf contract on any host.
- No MCP server, no A2A agent card, no /llms.txt, no /.well-known document.
- No webhooks or event subscriptions; asynchronous delivery is batch reporting feeds and file uploads.
- No public pricing, no terms of service, no SLA - all contract-bound and confidential.

## Source
- [GitHub org](https://github.com/appnexus)
- [Company website (301s to xandr.com, which 301s to about.ads.microsoft.com)](https://www.appnexus.com)
- Note: the former documentation host docs.xandr.com no longer resolves.