BidRequest.user

User

The human behind the request: identifiers, audience segments and consent.

Fields

Field	Type	Level	Description
id	string	optional	Exchange-specific user identifier.
buyeruid	string	optional	Bidder-specific user identifier, from a cookie sync.
eids	object[]	optional	Extended identifiers from third-party identity providers.
data	object[]	optional	Third-party audience data segments.
consent	string	optional	The TCF consent string.
geo	object	optional	The user's home location, as distinct from the device's current one.
yob	integer	optional	Year of birth as a four-digit integer.
gender	string	optional	Gender: M, F or O.

Example

{
  "id": "55816b39711f9b5acf3b90e313ed29e51665623f",
  "buyeruid": "545678765467876567898765678987654",
  "consent": "CPcqBLhPcqBLhAcABBENCZ…",
  "eids": [
    {
      "source": "example-id.com",
      "uids": [{ "id": "abc123", "atype": 1 }]
    }
  ]
}

What matters in practice

eids is where identity now lives. As third-party cookies became unreliable, the alternative identifiers — publisher-provided IDs, hashed email-derived IDs, and the rest — moved into this array rather than into buyeruid, so an integration reading only buyeruid will see addressability collapse while the request in front of it is carrying several usable identifiers. Note also that user.geo is the user's home location and device.geo is where they are now; conflating them is a quiet targeting bug.

Related objects

Field names, types and requirement levels from the IAB Tech Lab OpenRTB 2.6 specification (2.6-202211), verified 30 July 2026. The practice notes are not spec text.