Bid.impid

The ID of the impression this bid is for, copied from Imp.id in the request. Required.

CurrentstringRequiredSince 2.0

Field facts

Path: seatbid.bid.impid
Object: Bid
Type: string
Requirement: Required
Added: OpenRTB 2.0
Spec section: 4.2.3

How it is used

Copy the value exactly. In a request with several impressions, a wrong impid either invalidates the bid or places it on a different slot than the one you priced.

Example

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

{
  "seatbid": [
    {
      "bid": [
        {
          "impid": "1"
        }
      ]
    }
  ]
}

Common mistakes

Returning a placement or tag ID instead of Imp.id (openrtb.bid.impid_unknown).
Hard-coding "1" because single-impression test requests always used it.

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	Yes	No
2.3 to 2.6-202606	string	Yes	No

Related fields

Other Bid fields

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