How to Add Google Ad Exchange (AdX) Demand to Prebid.js: A Step-by-Step Guide

To add Google Ad Exchange (AdX) demand to your Prebid setup, you need to integrate the Google Ad Manager (GAM) with Prebid.js. Here’s a step-by-step guide to help you set it up:

Step 1: Set Up Google Ad Manager (GAM)

1. Ensure you have a Google Ad Manager account with Ad Exchange enabled.
2. Create Ad Units in GAM for the placements where you want to serve ads.
3. Create Line Items and Orders:
   • Create Price Priority line items for direct-sold campaigns.
   • Create Header Bidding line items for Prebid demand.
   • Ensure the Header Bidding line items have the correct pricing and targeting.

Step 2: Configure Prebid.js

1. Install Prebid.js:

• Include the Prebid.js library in your website. You can use the Prebid.js CDN or host it yourself.

<script async src="https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js"></script>

2. Configure Ad Units:

• Define your ad units in the Prebid.js configuration. Each ad unit should match the ad unit codes in GAM.

var adUnits = [{
    code: 'div-gpt-ad-123456789-0', // Match this with your GAM ad unit code
    mediaTypes: {
        banner: {
            sizes: [[300, 250], [728, 90]]
        }
    },
    bids: [{
        bidder: 'gam',
        params: {
            adUnitCode: 'div-gpt-ad-123456789-0', // Match with GAM ad unit code
            sizes: [[300, 250], [728, 90]]
        }
    }]
}];

3. Enable Google Ad Manager as a Bidder:

• Add the gam bidder to your Prebid.js configuration.

var pbjs = pbjs || {};
pbjs.que = pbjs.que || [];

pbjs.que.push(function() {
    pbjs.addAdUnits(adUnits);

    pbjs.setConfig({
        debug: true,
        enableSendAllBids: true // Send all bids to GAM
    });

    pbjs.requestBids({
        timeout: 1000,
        bidsBackHandler: function() {
            pbjs.setTargetingForGPTAsync();
            googletag.pubads().refresh();
        }
    });
});

4. Enable Send All Bids:

• Ensure enableSendAllBids is set to true in the setConfig method. This sends all bids to GAM for header bidding.

Step 3: Set Up GPT (Google Publisher Tag)

1. Include GPT in Your Page:

• Add the GPT script to your website.

<script async src="https://securepubads.g.doubleclick.net/tag/js/gpt.js"></script>

2. Define GPT Ad Slots:

• Define ad slots that match your Prebid ad units.

googletag.cmd.push(function() {
    googletag.defineSlot('/123456789/div-gpt-ad-123456789-0', [[300, 250], [728, 90]], 'div-gpt-ad-123456789-0').addService(googletag.pubads());
    googletag.pubads().enableSingleRequest();
    googletag.enableServices();
});

Step 4: Test Your Setup

1. Check the Console:

• Use your browser’s developer tools to check for errors in the console.

2. Verify Bids:

• Use the Prebid.js debug mode (pbjs.setConfig({ debug: true })) to verify that bids are being sent and received correctly.

3. Check GAM:

• Ensure that the bids are being passed to GAM and that the correct line items are being triggered.

Step 5: Optimize and Monitor

1. Adjust Timeouts:

• Adjust the timeout in pbjs.requestBids to balance latency and yield.

2. Monitor Performance:

• Use Prebid Analytics or GAM reporting to monitor the performance of your header bidding setup.

3. Add More Bidders:

• Consider adding more demand partners to increase competition and revenue.

Example Full Configuration

<script async src="https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js"></script>
<script async src="https://securepubads.g.doubleclick.net/tag/js/gpt.js"></script>
<script>
  var adUnits = [{
      code: 'div-gpt-ad-123456789-0',
      mediaTypes: {
          banner: {
              sizes: [[300, 250], [728, 90]]
          }
      },
      bids: [{
          bidder: 'gam',
          params: {
              adUnitCode: 'div-gpt-ad-123456789-0',
              sizes: [[300, 250], [728, 90]]
          }
      }]
  }];

  var pbjs = pbjs || {};
  pbjs.que = pbjs.que || [];

  pbjs.que.push(function() {
      pbjs.addAdUnits(adUnits);

      pbjs.setConfig({
          debug: true,
          enableSendAllBids: true
      });

      pbjs.requestBids({
          timeout: 1000,
          bidsBackHandler: function() {
              pbjs.setTargetingForGPTAsync();
              googletag.pubads().refresh();
          }
      });
  });

  googletag.cmd.push(function() {
      googletag.defineSlot('/123456789/div-gpt-ad-123456789-0', [[300, 250], [728, 90]], 'div-gpt-ad-123456789-0').addService(googletag.pubads());
      googletag.pubads().enableSingleRequest();
      googletag.enableServices();
  });
</script>

By following these steps, you should be able to successfully integrate Google Ad Exchange demand into your Prebid setup.