List of supported OpenRTB bid response fields

Your bidding API should respond with the parameters outlined below. Bid responses may contain multiple bids that correspond to a single impression.

Bid response object

The top level Bid Response Object and accompanying fields are below, followed by each lower level object contained within it.

Field Type Description


String; required

A unique identifier for this request, as indicated in the id field of the Bid Request Object.

Note: This must be equal to the value received in the bid request.


Array of Objects; required

The Seat Bid Object.


Object; optional

A custom IX Response Extension Object that contains information on SSL implementation.

Bid object

Field Type Description


String; required

The actual ad markup: XHTML if responding to a Banner Object; VAST XML if responding to a Video Object.


  • VAST-compliant notification IX Library™ is supported, but not recommended; additional lead time and integration tests are required in this case. Must include the notification macro.
  • If the bid request is secure, IX will check this field to ensure there are no insecure items. If insecure items are found, IX will discard the impression.


Array of Strings; required

The domain/landing page/brand to identify the advertiser; limited to 128 characters.

Note: Not required if the impression is passed on.


String; required

A unique identifier to represent this bid.


String; required

A unique identifier for this impression (indicated in the id field of the Impression Object); must be equal to the value received in the bid request.


Float; required

The bid price represented as cost per thousand impressions (CPM). By default, bidding is in dollars represented as floating point numbers (for example, 2.71828).

Optionally, you can configure to send bid price in cents and provide one or more numeric digits, such as 68 which represents a CPM of $0.68.


Array of Integers; optional

The creative type, as per the standard creative attributes list. We provide additional mapping for 500 Overlay.

Note: Pass only one attribute when possible (preferred).


String; optional

The app name or bundle being advertised (e.g. "") if applicable; unique ID across exchanges.


String; optional

A unique identifier for the direct deal associated with this bid; must be equal to the id provided in the Direct Deals Object if indicated in the request.

Note: This is always prioritized over a deal indicated in the Bid Extension Object.


String; optional

The billing notice URL called by an exchange when a winning bid becomes billable based on publisher criteria (for example, begin-to-render for web, 1-pixel is visible for app).


  • It should contain the ${AUCTION_PRICE} notification macro and should be a part of a valid URL.
  • It may contain the ${AUCTION_PRICE} notification macro in both the burl and adm fields. However, only impressions tracked from burl are considered billable.
  • Optionally, it may contain the ${SUPPLY_FEE} notification macro in both the burl and adm fields.

  • Not enabled for all partners by default. To enable burl, contact your IX Representative.

To learn more about the burl workflow at IX, see Using burl to request billing notifications.


Object; optional A custom Index Exchange Bid extension object which may contain information for this bid.

Bid ext object

Attribute Type Description


Object; sometimes sent

A skadn object passed as received from the DSP. See SKAdNetwork extension object below.

SKAdNetwork ext object

If the bid request included the BidRequest.imp.ext.skadn object, then a DSP could include the following object in their bid response. For more information on submitting the correctly formatted values, see Apple’s documentation. If the object is present in the response, then the SSP would submit the click data and signature to loadProduct() for attribution.

Attribute Type Description


String; sometimes sent

The version of SKAdNetwork desired. Must be 2.0 or above.


String; sometimes sent

The ad network identifier used in the signature. It should match one of the items in the skadnetids array in the request.


String; sometimes sent

The campaign ID compatible with Apple’s spec. In version 2.0, it should be an integer between 1 and 100, expressed as a string.


String; sometimes sent

The ID of advertiser’s app in Apple’s app store. It should match


String; sometimes sent

An id unique to each ad response. To learn more, see Apple’s documentation for the proper UUID format requirements.


String; sometimes sent

The ID of publisher’s app in Apple’s app store. It should match BidRequest.imp.ext.skad.sourceapp.


String; sometimes sent

The unix time in millis string used at the time of signature.


String; sometimes sent

The SKAdNetwork signature as specified by Apple.

Seatbid Bid Ext object

Field Type Description


Integer; optional

Specifies whether to turn Bid Translation service on or off for the associated bid.

0 = Bid Translation is not applied to the bid

1 = Bid Translation is applied to the bid

For more information, see Reducing CPM using Bid Translation.

Note: Contact your IX Representative if you want to pass this field.

SeatBid object

Field Type Description

Array of Objects; required

The Bid Object.


String; required

Unique identifier for the agency (when multiple agencies or independent direct clients use a DSP), with a value of:

  • Mediumint unsigned
  • 0 to 16777215


  • Required by default but can be disabled on a per-DSP basis if requested.
  • If you need to pass alphanumeric values in the seat field, please contact your IX Representative for further assistance.