BidRequest.bcat

A block list of advertiser categories in the taxonomy named by BidRequest.cattax, which defaults to IAB Content Taxonomy 1.0 codes such as IAB25 and IAB26. Bidders must not bid with creatives in these categories.

Currentstring arrayOptionalSince 2.0

Field facts

Path: bcat
Object: BidRequest
Type: string array
Requirement: Optional
Added: OpenRTB 2.0
Spec section: 3.2.1

How it is used

Exchanges compare it with Bid.cat, so a bid without categories cannot be checked. OpenRTB 2.0 admitted there was no advertiser taxonomy and suggested IAB content categories as a stand-in; 2.6 added cattax so sellers can name another taxonomy, such as the Ad Product Taxonomy.

Example

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

{
  "id": "req-1",
  "bcat": [
    "IAB25",
    "IAB26",
    "IAB7-39"
  ]
}

Common mistakes

Sending Content Taxonomy 2.x numeric IDs without setting cattax, so bidders read them as 1.0 codes.
Sending both bcat and acat.

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	Array of N String, default - ote that the	No	No
2.1	Array of ing N c a	No	No
2.2	array of strings	No	No
2.3 to 2.3.1	string array	No	No
2.4 to 2.5	string array	No	No
2.6-202210 to 2.6-202606	string array	No	No

Related fields

Other BidRequest fields

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