The IAB Tech Lab’s Video Ad Serving Template (VAST) specification is a universal XML schema for serving ads to digital video players and describes expected video player behavior when executing VAST-formatted ad responses. VAST opens up the in-stream digital video advertising marketplace and reduces expensive technical barriers, encouraging advertisers to increase video ad spend.
VAST4 was released in January of 2016. With the proliferation of devices and screen sizes over the last few years, this release was focused on meeting the challenges around delivering video ads efficiently to this wide variety of devices. This included features like separation of media files from verification and interactive code, a mezzanine file for server-side ad insertion, etc.
VAST 4.1 was released in November 2018 with support for Ad Requests, Ad verification with Open Measurement, and integration of DAAST for Audio ads. VAST 4.2 was released in June 2019 with support for interactivity with SIMID.
Further updates to VAST to support initiatives including the CTV Ad Portfolio and ACIF (Ad Creative ID Framework) are also included in VAST 4.x but they have also been added to earlier versions (2.x and 3.x) via the VAST Addendum. You can access all of the GitHub repositories using the links below.
Below you will find a Version History Timeline. To view the specifications, you should look at the IAB Tech Lab GitHub for VAST.
| Version | Release Date |
| VAST Addendum for CTV 2024 Includes ACIF Support for Ad Registration, Icons to Support DSA, and updates relating to the need for higher resolution creative on larger screens | July 2024 |
| VAST Addendum for attribution reporting Supports APIs that enable registering event URLs, includes attribute to identify URLs for potential attribution reporting. | July 2023 |
| VAST 4.3 You should also review the VAST CTV Addendum 2024 including Ad Creative support for VAST 4.3 | December 2022 |
VAST 4.2 Secure Interactive Media Interface Definition (SIMID) – the replacement for VPAID for interactive use cases and a few other minor updates. You should also review the VAST CTV Addendum CTV2024 including Ad Creative support for VAST 4.2 | June 2019 |
VAST 4.1 Updates for Improved Ad Verification, Ad Creative Measurement, Server-Side Ad Insertion and Integration of Audio Advertising You should also review the VAST CTV Addendum 2024 including Ad Creative support for VAST 4.1 | August 2017 |
VAST 4.0 You should also review the VAST CTV Addendum 2024 including Ad Creative support for VAST 4.0 | January 2016 |
VAST 3.0 You should also review the VAST CTV Addendum 2024 including Ad Creative support for VAST 3.0 | July 2012 |
VAST 2.0 You should also review the VAST CTV Addendum 2024 including Ad Creative support for VAST 2.0 | March 2012 |
| VAST 1.0 | No longer supported |
IAB Tech Lab Releases VAST 4.1 (Blog post)
IAB Tech Lab Releases VAST 4.1 for Public Comment (Press Release)
Five Use Cases for Video Ad Serving (PDF)
IAB Digital Video In-Stream Ad Format Guidelines (PDF)
Understanding & Adopting VAST 4.0 (Webinar)
Tech Lab CodeBank: VAST (GitHub)
Video Multiple Ad Playlist (VMAP)
Video Player-Ad Interface Definition (VPAID) – Deprecated, replaced with SIMID
Secure Interactive Media Interface Definition (SIMID)
DAA Ad Marker Implementation Guidelines for Video (PDF)
VAST 4.0 Arrives, Championing the Technology Behind the Growth of Digital Video Advertising (Blog)