Process the Request

  • Google's real-time bidding bid requests are sent as HTTP POST requests in OpenRTB JSON or Protobuf format, requiring parsing to access the BidRequest object.

  • Processing bid requests involves parsing the request, identifying billing IDs, using dictionary files for identifiers, leveraging bidder URL macros, and understanding mobile app ID extraction and Open Bidding fields.

  • Real-time feedback on previous bids is available to Authorized Buyers and Open Bidding participants, including creative status, minimum bid to win, and sampled mediation CPMs for first-price auctions, aiding in bidding strategy improvement.

  • Bid flattening breaks down complex bid requests into simpler ones, sharing the same BidRequest.ext.google_query_id and applied for opportunities with multiple ad formats, deals, varying video durations, and video pods.

A real-time bidding interaction begins when Google sends a bid request to your application. This guide explains how to code your application to process the bid request.

Parse request

Google sends a bid request serialized in either OpenRTB JSON or Protobuf formats, attached as the payload of an HTTP POST request. The format received depends on the configuration of your endpoint. See Example bid request for an example.

You must parse this request to receive the serialized BidRequest. If you are using the Protobuf format, you must download openrtb.proto and openrtb-adx.proto from the reference data page, and use them to generate a library that can be used to parse the BidRequest message. For example, the following C++ code parses a request given a POST payload in a string: 

string post_payload = /* the payload from the POST request */;
BidRequest bid_request;
if (bid_request.ParseFromString(post_payload)) {
  // Process the request.
}

Once you have the BidRequest you can then work with it as an object, extracting and interpreting the fields you need. For example, in C++ iterating through deals in an OpenRTB `BidRequest` could look like the following:

for (const BidRequest::Imp::Pmp::Deal& deal : pmp.deals()) {
  DoSomething(deal.id(), deal.wseat());
}

Billing IDs

You receive a bid request when a publisher's ad inventory is targeted by one or more of your pretargeting configurations. BidRequest.imp.ext.billing_id will be populated with the billing IDs of any eligible buyers, and relevant pretargeting configurations. Additionally, for deal inventory, you can find billing IDs associated with the relevant buyers using BidRequest.imp.pmp.deal.ext.billing_id. Only billing IDs of buyers included in the bid request may be specified when placing a bid.

If multiple billing IDs are included in the bid request, you must specify the billing ID of the buyer you intend to attribute your bid to with the BidResponse.seatbid.bid.ext.billing_id field.

imp {
  ext {
    // The billing IDs of all of your matching pretargeting configs and eligible child seats are
    // stored in a flat list here.
    billing_id: 123
    billing_id: 456
    billing_id: 789
  }
  pmp {
    // All eligible deals are stored in a single flat list.
    deal {
      id: 1000
      ext {
        // The specific billing IDs eligible to bid on this deal are indicated here.
        billing_id: 789
      }
      ...
    }
    deal {
      id: 2000
      ext {
        billing_id: 123
        billing_id: 456
      }
      ...
    }
  }
  ...
}
...

Determine blocked categories

When you place a bid, the included creative must not have detected categories that the publisher blocked. Otherwise the bid is filtered from the auction.

You can find the blocked categories for an impression by reviewing the BidRequest.bcat field, which is populated with categories in the taxonomy configured for your account.

The following example shows blocked categories based on a configured ad category taxonomy:

IAB Content Taxonomy 1.0

// Bid request
{
  // Indicates the blocked categories using IAB Content 1.0 Taxonomy.
  "bcat": [
    "IAB9-9",  // Cigars
    "IAB8-18"  // Wine
  ]
  "imp": {
    ...
  }
}
      
// Bid request
{
  // Indicates the blocked categories using Google Ad Category Taxonomy.
  "bcat": [
    "10138",  // Cigar and tobacco collecting
    "10080",  // Tobacco
    "11649",  // Wine
    "10674",  // Wine collecting
    "13008"   // Wine clubs
  ]
  "imp": {
    ...
  }
}

Dictionary files

The bid request uses identifiers defined in dictionary files, which are available on the reference data page.

Bidder URL macros

Optionally, some information from the BidRequest can be inserted into bidding endpoint URLs using macros. If you configure an endpoint URL with one or more macros, they will be expanded if that information is present in the bid request. This can be useful, for example, if you would like to perform load balancing based on information in the BidRequest. Contact your account manager to request support for new macros.

MacroDescription
%%GOOGLE_USER_ID%%

Replaced with the Google User ID found in BidRequest.user.id. For example, the bidder URL http://google.bidder.com/path?gid=%%GOOGLE_USER_ID%% will be replaced with something like http://google.bidder.com/path?gid=dGhpyBhbiBleGFtGxl at request time.

If the Google User ID is unknown, the empty string is substituted, with a result similar to

http://google.bidder.com/path?gid=
%%HAS_MOBILE%%

Replaced with 1 to indicate that the bid request is from a mobile device, or 0 otherwise. This is based on the value of BidRequest.device.devicetype, where mobile devices are indicated by HIGHEND_PHONE (4) or Tablet (5).
%%HAS_VIDEO%%

Replaced with 1 to indicate that the bid request contains video inventory, or 0 otherwise. This is based on whether BidRequest.imp.video is populated in the bid request.
%%HOSTED_MATCH_DATA%%

Replaced with a value based on BidRequest.user.buyeruid.

%%MOBILE_IS_APP%%

Replaced with 1 to indicate that the bid request is for mobile app inventory, or 0 otherwise. This is based on whether BidRequest.app is populated.

Find mobile app ID from transaction URL

Mobile application transactions will report URLs that look like this:

mbappgewtimrzgyytanjyg4888888.com

Use a base-32 decoder to decode the portion of the string in bold (gewtimrzgyytanjyg4888888).

You can use an online decoder, but you'll have to capitalize the letters and replace trailing 8s with = values.

So decoding this value: 

GEWTIMRZGYYTANJYG4======
 results in: 
1-429610587
 The string 429610587 is the app ID for the iOS app iFunny.

Here's another example. The reported URL is: 

mbappgewtgmjug4ytmmrtgm888888.com
 Decoding this value: 
GEWTGMJUG4YTMMRTGM======
 results in: 
1-314716233
 The result 314716233 is the app ID for the iOS app TextNow.

Find mobile app name from transaction URL

Here's an example of getting the app name. The reported URL is as follows: 

mbappMFUXELTDN5WS42DZOBQWQLTJN4XHG3DJORUGK4Q888.com
 Decoding this value: 
MFUXELTDN5WS42DZOBQWQLTJN4XHG3DJORUGK4Q===
 results in: 
air.com.hypah.io.slither
 The result equates to the Android app slither.io.

Open Bidding fields

Bid requests sent to exchange and network bidders participating in Open Bidding are similar to those of Authorized Buyers participating in standard real-time bidding. Open Bidding customers will receive a small number of additional fields, and a few existing fields may have alternative uses. These include the following:

OpenRTB Details
BidRequest.imp.ext.dfp_ad_unit_code

Contains the publisher's Ad Manager network code followed by the ad unit hierarchy, separated by forward slashes.

As an example, this would appear with formatting similar to: /1234/cruises/mars.
BidRequest.user.data.segment

Repeated key-value pairs sent from publisher to exchange bidder.

You can determine that the values are key-value pairs sent by the publisher when BidRequest.user.data.name is set to “Publisher Passed”.

Declare allowed vendors

Technology vendors which provide services such as research, remarketing, and ad serving may play a role in the interaction between buyers and sellers. Only vendors which Google has vetted for participation in Authorized Buyers interactions are allowed.

To understand the BidRequest and create your BidResponse, you need to be aware of the two different possibilities for declaring technology vendors:

  1. Some vendors don't need to be declared; these vendors are listed in Ad Manager Certified External Vendors.
  2. Other vendors can only participate if they are declared in the BidRequest:
    • In the BidRequest, the BidRequest.imp.ext.allowed_vendor_type field specifies which vendors the seller allows. Vendors that will be sent in the allowed_vendor_type are listed in the vendors.txt dictionary file.

Example bid request

The following examples represent human-readable samples of the Protobuf and JSON requests.

OpenRTB Protobuf

OpenRTB JSON

To convert the bid request into a binary form, like you would get from the POST payload in a real request, you can do the following (in C++). Note, however, that this is not applicable to OpenRTB JSON.

string text_format_example = /* example from above */;
BidRequest bid_request;
if (TextFormat::ParseFromString(text_format_example, &bid_request)) {
  string post_payload;
  if (bid_request.SerializeToString(&post_payload)) {
    // post_payload is a binary serialization of the protocol buffer
  }
}

Real-time feedback

Real-time feedback is available to Authorized Buyers, as well as exchanges and networks using Open Bidding.

Real-time feedback populates BidRequest.ext.bid_feedback based on the outcome of one or more bids you placed earlier, and can be used to find details such as whether the bid won the auction, or the minimum bid needed to have won the auction. Contact your account manager to enable real-time feedback.

In addition to the default fields sent in Bid Response Feedback, you can also send custom data in the bid response using the BidResponse.seatbid.bid.ext.event_notification_token field. The event_notification_token is arbitrary data known only to the bidder that might help with debugging, for example: a new targeting ID or bidding ID representing a new tactic, or metadata associated with the creative known only to the bidder. For details, see the OpenRTB Extensions Protocol Buffer file.

When Authorized Buyers sends a bid request to a bidder, the bidder replies with a BidResponse. If the bidder has real-time feedback enabled, then in a subsequent bid request, Authorized Buyers sends feedback on the response in a BidFeedback message:

message BidFeedback {
  // The unique id from BidRequest.id.
  optional string request_id = 1;

  // The status code for the ad. See creative-status-codes.txt in the
  // technical documentation for a list of ids.
  optional int32 creative_status_code = 2;

  // Deprecated. This field is not populated and will be removed after March,
  // 2025. If the bid won the auction, this is the price paid in your account
  // currency. If the bid participated in the auction but was out-bid, this
  // is the CPM that should have been exceeded in order to win. This is not
  // set if the bid was filtered prior to the auction, if the publisher or
  // winning bidder has opted out of price feedback or if your account has
  // opted out of sharing winning prices with other bidders. For first-price
  // auctions, minimum_bid_to_win is populated instead of this field.
  optional double price = 3 [deprecated = true];

  // The minimum bid value necessary to have won the auction, in your account
  // currency. If your bid won the auction, this is the second highest bid
  // that was not filtered (including the floor price). If your bid didn't win
  // the auction, this is the winning candidate's bid. This field will only be
  // populated if your bid participated in a first-price auction, and will not
  // be populated if your bid was filtered prior to the auction.
  optional double minimum_bid_to_win = 6;

  // Billable event rate multiplier that was applied to this bid during
  // ranking. The adjustment reflects the likelihood that your bid would
  // generate a billable event (namely, the ad renders successfully) if it won
  // the auction, relative to the probability that other bids generate a
  // billable event if they won the auction. This adjustment can be larger or
  // smaller than 1. This affects the final ranking in the auction only; in
  // particular, this multiplier does not affect the payment or whether the
  // bid clears any floor price.
  optional float billable_event_rate_bid_adjustment = 13 [default = 1];

  // When a publisher uses an RTB auction and waterfall-based SDK mediation on
  // the same query, the winner of the real-time auction must also compete in
  // a mediation waterfall (which is ordered by price) to win the impression.
  // If the bid participated in the auction and there was no waterfall, the
  // value of this field is 0. If the bid participated in the auction and
  // there was a waterfall, the value of this field is a price representing a
  // sample bid from the eligible mediation networks that were higher than the
  // auction winner, weighted by expected fill rate. This field can be used
  // in conjunction with minimum_bid_to_win to train bidding models. The CPM
  // is in your account currency.
  optional double sampled_mediation_cpm_ahead_of_auction_winner = 8;

  message EventNotificationToken {
    // The contents of the token.
    optional string payload = 1;
  }

  // The token included in the corresponding bid.
  optional EventNotificationToken event_notification_token = 4;

  // The creative ID included in the corresponding bid.
  optional string buyer_creative_id = 5;
}

From this message, the first field you should check is bid_feedback.creative_status_code; you can find the code meaning in creative-status-codes.txt. Note that if you win the bid, you can opt out from the price feedback. For more information, see How to opt-out.

The real-time feedback includes the bid request ID and one of the following:

Auction outcome Real-time feedback
The buyer didn't submit a bid. Nothing.
The buyer submitted a bid that was filtered out before reaching the auction. The creative status code (creative-status-codes.txt).
The buyer submitted a bid but lost the auction. The creative status code 79 (outbid in auction).
The buyer submitted a bid that won the auction. The clearing price and creative status code 1.

For an app impression and a creative status code of 83, the app publisher could have been using a mediation waterfall and therefore the winning bid would have competed against other demand in the publisher's passback waterfall chain. Learn how to use sampled_mediation_cpm_ahead_of_auction_winner when bidding.

Sample

The following is a sample of real-time feedback as seen in supported protocols:

OpenRTB Protobuf

OpenRTB JSON

Build a bidding model for first-price auctions

After placing a bid in a first-price auction, you will receive real-time feedback including the minimum_bid_to_win and sampled_mediation_cpm_ahead_of_auction_winner fields if the bid was not filtered from the auction. These signals can be used to inform your bidding logic on how much higher or lower your bid could have been in order to win the impression.

  • minimum_bid_to_win: The minimum bid that could have been placed to win the real-time bidding auction. If you won the auction, this will be the lowest bid you could have placed while still winning. If you lost the auction, this will be the winning bid.
  • sampled_mediation_cpm_ahead_of_auction_winner: If there are other networks in the mediation chain, the value of this field is a price representing a sample bid from one of the eligible mediation networks that were higher than the auction winner, weighted by expected fill rate. This will be set to 0 if none of the networks in the mediation chain are expected to fill, or if the publisher does not use SDK mediation.

How it works

In order to describe the calculations used to determine the possible values for minimum_bid_to_win and sampled_mediation_cpm_ahead_of_auction_winner, we first need to define the following:

  • The following represents the CPMs in the mediation chain in descending order:
    \[C_1, C_2, …, C_n\]
  • The following represents the corresponding fill rates for the CPMs in the mediation chain:
    \[f_1, f_2, …, f_n\]
  • The following is a function used to determine the expected CPM and its probability from mediation chain element \(i\), based on the given fill rate:
    \(X_i = \{C_i\) with probability \(f_i\); \(0\) with probability \(1 - f_i\}\)
  • The final winning mediation chain will be:
    \[\{C_1, C_2, …, C_K, W\}\]
    where \(W\) is the winning bid, and \(C_K > W >= C_{K+1}\)
  • The reserve price, or floor, is denoted as \(F\).
  • The runner-up bid is denoted as \(R\).
Calculations for auction winner
Field Calculation
minimum_bid_to_win
\(max\{F, R, X_{K+1}, …, X_n\}\)
sampled_mediation_cpm_ahead_
of_auction_winner
\(\{C_i\) with probability \(\prod_{j=1}^{i-1}(1-f_j) \cdot f_i \div \prod_{j=1}^{K}(1-f_j)\}\)
For \(1 <= i <= K\).
Calculations for auction loser
Field Calculation
minimum_bid_to_win
\(max\{F, W\}\)
sampled_mediation_cpm_ahead_
of_auction_winner
\(max\{X_1, …, X_K\}\)

Example with a simple mediation chain

Assume a publisher uses both real-time bidding and an SDK mediation chain as follows:

SDK Mediation Chain Expected CPM Fill Rate
Network 1 \(C_1 = $3.00\) \(f_1 = 5\%\)
Network 2 \(C_2 = $2.00\) \(f_2 = 45\%\)
Network 3 \(C_3 = $0.50\) \(f_3 = 80\%\)
Network 4 \(C_4 = $0.10\) \(f_4 = 85\%\)

Assume the following as the result of the RTB auction:

RTB Auction CPM
Auction Winner (W) $1.00
Auction Runner-UP (R) $0.05
Reserve Price / Floor (F) $0
Bid that won the auction

The following is an example of how values and probabilities for minimum_bid_to_win and sampled_mediation_cpm_ahead_of_auction_winner are calculated for a bid that won.

minimum_bid_to_win Probability
\(max(F, R, C_3) = $0.50\) \(f_3 = 80\%\)
\(max(F, R, C_4) = $0.10\) \((1-f_3) \cdot f_4 = 17\%\)
\(max(F, R, 0) = $0.05\) \((1-f_3) \cdot (1-f_4) = 3\%\)
sampled_mediation_cpm_
ahead_of_auction_winner		 Probability
\(C_1 = $3.00\) \(f_1 \div (1-(1-f_1) \cdot (1-f_2)) =~ 10.5\%\)
\(C_2 = $2.00\) \(((1-f_1) \cdot f_2) \div (1-(1-f_1) \cdot (1-f_2)) =~ 89.5\%\)
Bids that lost the auction

The following is an example of how values and probabilities for minimum_bid_to_win and sampled_mediation_cpm_ahead_of_auction_winner are calculated for a bids that lost.

minimum_bid_to_win Probability
\(max(F, W) = $1.00\) \(100\%\)
sampled_mediation_cpm_
ahead_of_auction_winner		 Probability
\(C_1 = $3.00\) \(f_1 = 5\%\)
\(C_2 = $2.00\) \((1-f_1) \cdot f_2 =~ 42.8\%\)
\(0\) \((1-f_1) \cdot (1-f_2) =~ 52.2\%\)

Bid flattening

Bid flattening describes the processing of a single complex BidRequest into multiple bid requests that are sent to your application. When a bid request is flattened, you can tell which bid requests were part of the original because they will have an identical value in the BidRequest.ext.google_query_id field.

Bid flattening is enabled by default, but you can contact your account manager if you would prefer to disable it.

Ad formats

Some ad opportunities can accept multiple formats. With bid flattening, each format is sent in a distinct bid request where attributes such as eligible billing IDs are relevant to the format specified in the request.

Bid requests containing the following formats will be flattened into distinct bid requests:

  • Banner
  • Video
  • Audio
  • Native

Ad format flattening example

Below is an example showing a simplified OpenRTB JSON bid request without ad format flattening in comparison to an equivalent set of flatenned requests:

Pre-flatten

Post-flatten

Deals

An ad opportunity for a given bidder can be applicable to various deal types, in addition to the open auction. With bid flattening for deals, one bid request will be sent for the open auction, and one for each type of fixed-price deal. In practice, ad constraints can differ between auctions and fixed-price deal types, for example, for a given video ad opportunity that is available to both the open auction and a fixed-price deal, a bidder will receive distinct bid requests for each where constraints such as maximum ad duration and whether skippable ads are allowed can differ. As a result, flattening applied to the ad opportunity lets you more easily discern the ad constraints for the open auction and the fixed-price deal.

Skippability and Video Duration

The OpenRTB spec doesn't have separate fields for specifying the maximum video durations of skippable and non-skippable ads. Google's implementation uses bid flattening to distinguish between these using the existing BidRequest.video.maxduration and BidRequest.video.skip fields.

The following is an example of how video inventory is flattened when the maximum duration of a non-skippable ad is 15 and the maximum duration of a skippable ad is 60.

Example max_ad_duration skip (true OR false)
Original request without flattening 15 true
Flattened request #1: Non-skippable 15 false
Flattened request #2: Skippable 60 true

Skippable video duration bid request flattening will only take place when these conditions are met:

  • The request allows video.
  • Both skippable and non-skippable videos are allowed, and the two respective max durations differ in value.
  • This request is Private Auction or Open Auction-eligible.

You can opt out from this type of flattening by contacting your technical account manager. When disabled, and the publisher allows both skippable and non-skippable video ads with different maximum durations based on skippability, skip would be set to true and maxduration would be set to whichever duration is shorter between skippable and non-skippable ad constraints.

Video pods

Bid requests for a video pod with multiple ad opportunities are flattened, such that each bid request is for an individual ad opportunity from that pod. This enables you to bid on multiple ad opportunities for a given pod.

Open Measurement

Open Measurement lets you specify third-party vendors that provide independent measurement and verification services for ads served to mobile app environments.

You can determine whether a publisher supports Open Measurement in the bid request by checking whether the ad opportunity excludes the OmsdkType: OMSDK 1.0 attribute found in Publisher-excludable creative attributes. This would be found under the battr attribute for Banner or Video, depending on the format.

For more information on how to interpret bid requests containing Open Measurement signals, refer to the Open Measurement SDK Help Center article.

Sample bid requests

The following sections show sample bid requests for different ad types.

App banner

OpenRTB Protobuf

OpenRTB JSON

App interstitial

OpenRTB Protobuf

OpenRTB JSON

App interstitial video

OpenRTB Protobuf

OpenRTB JSON

App native

OpenRTB Protobuf

OpenRTB JSON

Web video

OpenRTB Protobuf

OpenRTB JSON

Mobile web banner for exchange bidder

OpenRTB Protobuf

OpenRTB JSON

Multiformat Native and Video

OpenRTB Protobuf

OpenRTB JSON