Magnite Exchange API (xAPI) OpenRTB Extensions

Magnite's Exchange API (xAPI) protobuf extensions to the IAB OpenRTB 2.x protobuf definitions, published in the open on GitHub. Defines Magnite-specific OpenRTB extension fields (extension IDs in the 5100-5299 range) for the AdEngine bidding endpoint, including window/iframe geometry, key-value pairs and supply-chain signals used by demand partners bidding into the Magnite exchange.

Work with this as data

Every API here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for apis

7 MCP tools reach this
  • find_apisBrowse and filter every API in the catalog.
  • get_api_artifactsOne API's artifacts, grouped by type.
  • get_openapiThe primary OpenAPI for this API.
  • find_similar_apisAPIs that look like this one.
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

curl for this page
This API
curl "https://apis.io/api/v1/apis/rubicon-project-openrtb-xapi"
All apis
curl "https://apis.io/api/v1/apis?limit=25"

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no email required.

A second provider on the same verified email joins the account you already have.

API entry from apis.yml

apis.yml Raw ↑
aid: rubicon-project-openrtb-xapi
name: Magnite Exchange API (xAPI) OpenRTB Extensions
description: Magnite's Exchange API (xAPI) protobuf extensions to the IAB OpenRTB 2.x protobuf definitions,
  published in the open on GitHub. Defines Magnite-specific OpenRTB extension fields (extension IDs in
  the 5100-5299 range) for the AdEngine bidding endpoint, including window/iframe geometry, key-value
  pairs and supply-chain signals used by demand partners bidding into the Magnite exchange.
humanURL: https://github.com/MagniteEngineering/xapi-proto
baseURL: https://github.com/MagniteEngineering/xapi-proto
tags:
- OpenRTB
- Real-Time Bidding
- Protobuf
properties:
- type: Protobuf
  url: grpc/rubicon-project-openrtb-xapi.proto
- type: SourceCode
  url: https://github.com/MagniteEngineering/xapi-proto