What is a seatbid, and why is my response's seatbid empty?

Answer

seatbid is the array grouping bids by bidder seat: each SeatBid carries an optional seat identifier and a bid array with at least one bid. A BidResponse with no seatbid, or with SeatBid objects whose bid arrays are empty, is a no-bid as far as the auction is concerned. If your engine intends to bid but seatbid comes out empty, look at your response assembly: bids filtered late (floor, budget, creative approval) after the response shell was built is the classic cause. If you mean to no-bid, prefer HTTP 204 or set nbr so the intent is explicit.

Go deeper

More questions on debugging, no-bids, and validation

All 93 questions are listed in the OpenRTB FAQ.