What is the ext field in OpenRTB and how do extensions work?
Answer
ext is a placeholder object for exchange-specific extensions, and by convention it may appear on any OpenRTB object. The spec deliberately leaves its structure undefined; an exchange using extensions is responsible for documenting them to its bidders. IAB Tech Lab hosts well-known community extensions in its GitHub repository, and successful extensions often get promoted into the core spec later: regs.ext.gdpr, user.ext.consent, and source.ext.schain in 2.5 all became first-class fields (regs.gdpr, user.consent, source.schain) in 2.6. Validators can only check documented fields, so undocumented ext payloads are effectively opaque.
Fields in this answer
| Field | Type | Since | Status in 2.6 |
|---|---|---|---|
regs.gdpr | integer | 2.6-202204 | Current |
user.consent | string | 2.6-202204 | Current |
source.schain | object | 2.6-202204 | Current |
Go deeper
More questions on openrtb basics and the bid request
- What is OpenRTB? OpenRTB is the IAB Tech Lab standard that defines the JSON messages ad exchanges and bidders use to buy and sell impressions in real time.
- How does a real-time bidding auction work end to end? A user loads a page or app, the publisher's ad system asks an exchange to sell the impression, and the exchange sends an OpenRTB BidRequest over HTTP POST to many bidders at once.
- What's the difference between OpenRTB and Prebid.js? OpenRTB is a wire protocol; Prebid.js is a piece of software.
- Is header bidding the same as OpenRTB? No.
- What's the difference between an SSP, a DSP, and an ad exchange? From the protocol's point of view there are only two roles: the supply side sends OpenRTB bid requests and runs the auction, and the demand side receives them and bids.
- What is a bid request in programmatic advertising? A bid request is the JSON message an exchange sends to bidders to offer one or more impressions for sale.
All 93 questions are listed in the OpenRTB FAQ.