BidResponse.customdata

An optional string the bidder asks the exchange to store in the exchange's own cookie for this user, written in base85 cookie-safe characters. The exchange can send it back later in User.customdata.

CurrentstringOptionalSince 2.0

Field facts

Path: customdata
Object: BidResponse
Type: string
Requirement: Optional
Added: OpenRTB 2.0
Spec section: 4.2.1

How it is used

Support depends on the exchange, and cookie storage is unavailable on most app and CTV traffic. Any quotation marks inside the string must be escaped as JSON requires.

Example

Where the field sits in a payload, with everything else left out:

{
  "customdata": "seg8812k"
}

Version history

Added in OpenRTB 2.0, and present in the latest snapshot. The table shows how each version's spec text types the field.

Versions	Type in the spec	Required	Deprecated
2.0 to 2.2	string	No	No
2.3 to 2.6-202606	string	No	No

Related fields

User.customdata

Other BidResponse fields

For a walkthrough of the whole object, read Bid response anatomy.