Real-time bidding for developers

If you are a developer working on a real-time bidder, or are looking for detailed developer documentation, refer to the Ad Exchange Real-Time Bidding (RTB) Protocol

Introduction to the RTB Protocol

The following is an overview of the protocol:

  1. Processing the request

    Google sends a request to the client bidding application that describes an impression being auctioned. You'll need to implement code that interprets Google's request. After sending a request for a bid, Google will wait a fixed amount of time for a response. If nothing is received after that time, then the exchange will proceed with the auction using only bids that it has received.

  2. Building the response

    The client bidding application sends a response to Google that describes the bid, and includes an HTML snippet for the associated creative. Optionally, the client application can include one or more macros in the HTML snippet that Google will replace with appropriate values that can be used to customize how the creative is rendered. Alternatively, such customizations can be done in the HTML snippet that is returned without having to use macros. You'll need to implement code that creates and returns the response.

  3. Bid enters Open Auction

    The bid response is received and its bid enters the open auction, where it wins the impression because it is the highest bid. As a result, the creative specified in the response is placed.


Real-time bidder is designed to work with third-party bid engines and ad servers. To create a bidder, you need to be able to develop code that uses the real-time bidding protocol, and your bid engines or ad servers need to be able to address a high number of queries per second, within milliseconds.

Real-time bidder attempts to provide buyers with the same information they would receive if their ad tag were placed directly on the publisher's site, augmented with additional data, and filtered for information that should not be shared according to the seller's settings. This includes:

  • Information from the publisher's web page is passed to the buyer.
  • Additional information, such as site vertical and seller-declared restrictions, is added.
  • Site names, IP addresses, and cookies are hidden or anonymized based on the seller's settings.
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