Amazon DSP adds VAST 4 support for third-party video inventory in 34 countries
Thirty-four countries now fall under Amazon DSP's expanded support for VAST 4, the fourth-generation video ad serving specification maintained by IAB Tech Lab, following an Amazon Ads announcement on September 02, 2026. The rollout covers versions 4.0 through 4.3 on third-party publisher inventory. Nothing switches off and no deadline applies: the platform checks what each publisher's video player supports and returns the highest version it can handle, so VAST 2 and VAST 3 publishers keep being served as before while VAST 4 publishers start receiving VAST 4 automatically, with no election from the buyer. Advertisers running their own advertiser ad server can now apply VAST 4 tags to third-party inventory, removing a downgrade step that agencies with their own serving stack had been absorbing. Amazon's own properties, including Stores and Fire TV, continue to support only VAST 2 and VAST 3 creatives, and the announcement gives no timeline for changing that.
A single video campaign can now straddle two creative standards inside the same buy: Fire TV and Amazon Stores keep serving VAST 2 or VAST 3 impressions, while a compatible third-party publisher elsewhere in the 34-country footprint gets VAST 4 automatically. Measurement teams reconciling that campaign end up reading events produced under two different schemas, and a single master creative asset arrives conditioned differently depending on which player answered the call. The clearest operational gain sits with advertisers who run their own ad server: VAST 4 tags on third-party inventory now remove a downgrade step that agencies with their own serving stack had been absorbing, which is the part of the change most likely to alter day-to-day trafficking practice. Amazon frames the update as giving campaigns access to more premium supply and better cross-channel measurement, though it offers no figures to support that claim and no date for bringing Fire TV or Stores to the same standard.