Sending the win notice URL (nurl) in bid responses

DSPs
Last Updated: October 15, 2026•

The nurl (win notice URL) field lets a DSPClosed Demand-Side Platform (DSP). A software platform that automates bidding decisions in real-time and efficiently connects buyers and audiences through an ad exchange or SSP. Also known as a buy-side platform. receive a callback when its bid wins the Index auction. The notice is sent at auction time, before the ad is delivered, so it tells you that you won the Index auction and nothing more.

Note: A win notice is not a billing event. Winning the Index auction does not mean the impression was served, viewed, or billed. To confirm a billable impression, use the billing notification instead. See Sending the billing notice URL (burl) in bid responses and How Index counts impressions.

How nurl differs from burl

 nurlburl

When it fires

At auction time, immediately after the Index auction is decided.

When the impression is served.

What it means

Your bid won the Index auction. The ad may still not be delivered.

The impression was delivered and is billable.

Use it for

Provisional win signals, pacing, and real-time budget decisions.

Counting impressions and reconciling spend.

Counted as an impression

No

Yes

How to send it

Include the nurl field on the Bid object in your bid responseClosed An OpenRTB response that is sent by the DSP in response to the SSP's or ad exchange's bid request. It is an event directed back to the seller expressing a valuation for the request and conditions of sale.. The value must be a URL that Index can call.

Supported macros

Index supports only the following macro in nurl:

MacroDescription

${AUCTION_PRICE}

The clearing price for the Index auction, in dollars.

Note: Index does not support ${AUCTION_MIN_TO_WIN} or ${AUCTION_LOSS} in nurl. Those macros apply to loss notices. See Sending the loss notice URL (lurl) in bid responses.

Replacing ${AUCTION_PRICE} in a nurl does not make the impression billable. For how the macro behaves in adm and burl, see Auction price macros.

Delivery behavior

  • The notice is delivered as an HTTP callback, fired after the Index auction completes.

  • If the DSP does not accept the callback, Index retries until the notice expires.

  • A notice expires 30 minutes after it is generated. If it has not been accepted by then, it is not sent again.

Examples

An example bid response containing a nurl:

{
  "id": "1a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d",
  "seatbid": [
    {
      "bid": [
        {
          "id": "bid-001",
          "impid": "1",
          "price": 2.75,
          "adm": "<script src=\"http://adserver.dsp.com/ad.js?price=${AUCTION_PRICE}\"></script>",
          "nurl": "http://adserver.dsp.com/win?id=bid-001&price=${AUCTION_PRICE}"
        }
      ],
      "seat": "dsp-seat-1"
    }
  ],
  "cur": "USD"
}

If the bid wins, Index calls the following URL:

http://adserver.dsp.com/win?id=bid-001&price=2.75