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SSAI VAST Macros Guidance

Ad servers, measurement partners, and buyers need access to additional data from publishers to gain a clearer view into the environments they are serving into. In 2018, the IAB Tech Lab released a set of standardized VAST player macros to facilitate this transparency across any VAST environment. 

VAST player macros enable publisher’s media players to provide additional data points into ad requests. They cover passing details such as the user agent and app that the VAST ad is serving into. They are compatible with any VAST 2.0+ environment.

The IAB Tech Lab maintains an official list of over 50+ VAST macros. Given the extensivity of this list, and the constraints of URL length limits for HTTP GET requests the Digital Video Technical Standards Working Group developed the AdCOM based Common Ad Transport Standard (CATS) as a medium to longer term replacement for the macros, and all macros are being added in alignment with AdCOM. The SSAI VAST Macros Guidance helps direct SSAI providers and the industry toward an optimal set of macros relevant for SSAI use cases. The list contained within the SSAI VAST Macros Guidance has been curated for sharing basic user agent, environment, and content details that are critical to verification partners and buyers. 


Developed by the Digital Video Technical Standards Working Group


Katie Stroud
Senior Product Manager