VAST XML for Google Ad Manager

Google Ad Manager (GAM) is the dominant ad server for premium publishers globally. It serves VAST tags to players via the Google IMA SDK and handles VAST trafficking, wrapper resolution, and creative approval. This guide covers what your VAST tag must look like to traffic and deliver successfully in GAM — including the complete reference for VAST tag URL parameters.

Quick reference

GAM adds a wrapper layer

When you traffic a third-party VAST tag in GAM, GAM wraps it in its own VAST wrapper. This means that by the time a player (running IMA SDK) receives the tag, there is already one wrapper hop consumed. The IMA SDK limit is 4 hops total, so your third-party tag must resolve within 3 additional hops.

If you are trafficking a redirect that itself points to a programmatic SSP which adds more wrappers, you may be at or over the limit before the inline ad is reached.

VPAID deprecation

Google officially deprecated VPAID in GAM in 2022. While VPAID creatives can still be trafficked in some GAM configurations, Google's ad serving infrastructure and IMA SDK actively block VPAID on mobile, CTV, and a growing share of web inventory. New campaigns should use native video creatives with OMID <Verification> blocks for third-party measurement.

<!-- Modern approach: native video + OMID verification -->
<InLine>
  <AdVerifications>
    <Verification vendor="doubleverify.com-omid">
      <JavaScriptResource apiFramework="omid" browserOptional="true">
        <![CDATA[https://cdn.doubleverify.com/dvtp_src.js]]>
      </JavaScriptResource>
    </Verification>
  </AdVerifications>
  <Creatives>
    <Creative>
      <Linear>
        <MediaFiles>
          <MediaFile type="video/mp4" width="1920" height="1080"
                     bitrate="4500" delivery="progressive">
            <![CDATA[https://cdn.example.com/ad.mp4]]>
          </MediaFile>
        </MediaFiles>
      </Linear>
    </Creative>
  </Creatives>
</InLine>

VAST tag URL parameters

GAM VAST tags are URLs with query parameters sent to pubads.g.doubleclick.net/gampad/ads. Getting these parameters right is critical for ad serving, programmatic fill, brand safety signals, and privacy compliance.

When using the IMA SDK, it populates most required parameters automatically. In environments without the SDK (direct VAST calls, PAL, PAI), all required parameters must be set manually.

Note: For boolean parameters use 0/1 not false/true (e.g. vpmute=1).

Required parameters

Programmatic parameters

Required or recommended when monetising with programmatic demand. These parameters significantly affect bid prices and fill rates.

CTV / OTT parameters

Incorrect or missing CTV parameters lead to device misclassification, lower CPMs, and reduced programmatic fill.

Content targeting parameters

Pass video programming signals to buyers on CTV for improved contextual targeting.

Privacy parameters

Complete CTV tag example

A well-formed GAM VAST tag for a connected TV app:

https://pubads.g.doubleclick.net/gampad/ads
  ?iu=/6062/my-network/my-ctv-app
  &env=instream
  &gdfp_req=1
  &output=xml_vast4
  &sz=640x480
  &correlator=[CORRELATOR]
  &description_url=https%3A%2F%2Fwww.example.com%2Fshow%2Fepisode1
  &url=https%3A%2F%2Fwww.example.com%2Fshow%2Fepisode1
  &plcmt=1
  &vpa=auto
  &vpmute=0
  &dth=5
  &msid=com.example.myapp
  &an=My%20CTV%20App
  &rdid=[RDID]
  &idtype=rida
  &is_lat=0
  &ct_ch=My%20Channel
  &ct_ne=My%20Network
  &unviewed_position_start=1

Replace bracketed values with dynamic macros from your ad server or device SDK.

UniversalAdId for frequency capping

GAM uses <UniversalAdId> (VAST 4.0+) for cross-environment frequency capping and deduplication. Include a <UniversalAdId> with a consistent registry and ID value to enable cross-screen frequency management.

<UniversalAdId idRegistry="ad-id.org">8465903</UniversalAdId>

Creative approval and HTTPS

GAM requires HTTPS for all creative asset URLs. HTTP URLs may be rejected at upload time or fail silently at delivery on HTTPS pages. This applies to media file URLs, click-through URLs, and companion assets.

vastlint rules: VAST-2.0-duration-format, VAST-2.0-mediafile-url

Pre-flight checklist for Google Ad Manager

• No VPAID for new campaigns — use native video + OMID
• All creative asset URLs use HTTPS
• Wrapper chain depth ≤ 3 hops (GAM adds the 4th)
• MP4 H.264 <MediaFile> present
• <Duration> in HH:MM:SS format
• <Impression> with HTTPS URL present
• version attribute on root <VAST> element
• <UniversalAdId> for cross-screen campaigns (VAST 4.0+)
• Tag URL includes env, gdfp_req, iu, output, sz, correlator
• CTV tags include dth=5, msid, an, plcmt, vpa, vpmute

References

• Google Ad Manager — All VAST ad tag parameters
• Google Ad Manager — About VAST 4
• Google Ad Manager — Add a linear video creative to a line item
• IMA SDK — Video features and SDK versions (VAST/VPAID support matrix)
• Google Ad Manager — VAST video error codes

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