Bid response

A bid response is the OpenRTB message a bidder returns to an exchange for a bid request, containing zero or more bids, each with a price, a currency, the creative or its markup, the impression it applies to, the advertiser domain and, where relevant, the deal it is bidding into.

The BidResponse object carries id (matching the request), seatbid arrays grouped by buyer seat, each bid with impid, price, adm (markup) or nurl (win-notice URL), adomain, crid, dealid and creative attributes; a response may also carry cur and a no-bid reason nbr (OpenRTB 2.6, section 4.3). Prices are expressed as CPM. The exchange substitutes macros such as ${AUCTION_PRICE}, "clearing price using the same currency and units as the bid," into the win notice or markup after the auction (OpenRTB 2.6, section 4.4).

Two things about responses matter operationally. The response must arrive within tmax or it is discarded, so a bidder tunes for the 99th percentile, not the average. And the response is a legal statement: adomain and cat are what a publisher's brand-safety rules act on, and a wrong dealid is a billing dispute.

Example (one bid):

{ "id": "80ce30c53c16e6ede735f123ef6e32361bfc7b22", "cur": "USD",
  "seatbid": [{ "seat": "buyer-7", "bid": [{ "id": "b1", "impid": "1", "price": 2.10,
     "adomain": ["brand.example"], "crid": "cr-55", "dealid": "DL-2026-001",
     "nurl": "https://dsp.example/win?p=${AUCTION_PRICE}", "adm": "<div>...</div>", "w": 300, "h": 250 }] }] }

Related: bid request, deal ID, first-price auction, timeout.

Source: IAB Tech Lab, OpenRTB 2.6, sections 4.3 and 4.4.

1. OpenRTB 2.6, section 4.4