VAST vs. VPAID – What They Are, How They Work, And More!

Reading time: 5 minutes

Some consumers find video more compelling than text, easier to pay attention to, and easier for users to retain information. The proportion of internet traffic that is video is increasing exponentially. Today, videos account for 80% of internet traffic. This shift is changing the priorities for ad spend and how publishers can profit from video advertising.

To help facilitate the needs of publishers, tools like VAST[1] and VPAID have sprung up to bring these video ads[7] to customers. But the differences between these two services can be confusing. What is the difference between VAST and VPAID, and how do they fit into the bigger picture of video advertising?

What is VAST?

VAST (video ad serving template) is basically a script you run allowing video players to run ads and coordinate with ad servers[2]. Using VAST allows the ads to run exactly the way the publisher[8] wants on different devices like desktop, laptop, tablet, and mobile.

Using VAST, the publisher is able to give the video player instructions like:

  • Which ad to play
  • When the ad should play during the course of the video.
  • How long to run the ad before the user is allowed to skip it.
  • Where to direct users after they convert with the call to action (CTA)
  • Whether or not the ad can be skipped

Running VAST is a three step process.

  1. The video player sends a request to the ad server, asking it to fetch an ad.
  2. The ad server responds to the request by providing the media files and tracking URLs to the video player.
  3. The player then displays the ad and activates the tracking URLs, which allow related parties to track and measure the impression[3].

There have been multiple versions of VAST which have added to the script’s features. The Ad Ops[4] industry hasn’t been quick to adopt the latest versions as they are released. While the latest 4.0 version (and later) solves many of the problems that VAST has had in the past, there are still publishers who only support VAST 2.0 or 3.0.

As the tool has evolved, it has expanded what it is able to provide publishers.

  • VAST 1.0 – Supports MP4, 3GP, .MOV, play-pause-stop functions and linear tracking.
  • VAST 2.0 – Supports MP4, 3GP, .MOV, Flash, JavaScript, play-pause-stop functions, quartile event, and tracking for linear, non-linear, and companion ads.
  • VAST 3.0 – Supports all five ad formats, skippable ads, is OBA compliant, and better at reporting errors.
  • VAST 4.0 – Allows separate video and interactive files, mezzanine files, server stitching, viewability[5], verification, and advanced reporting features.
  • VAST 4.1 – Contains all of the features of version 4.0, working to make the service more stable.

Up until the implementation of VAST 4.0, the tool didn’t support all viewability standards. Users have also had problems with XML parsing, schema validation, and redirection timeout, all of which are currently being worked on to improve VAST. 

What is VPAID?

VPAID (video player ad interface) is a different script that lets ads interact with video players. The key difference between VAST and VPAID is that VPAID lets the publishers serve interactive ads to users, while VAST doesn’t support this capability. 

VPAID also records data on how users interact with the ads. So marketers are able to measure performance[6] more closely and publishers are able to more effectively leverage video ads to generate revenue.

VPAID makes ads interactive by enabling and tracking distinct events. Users can:

  • Click on different tabs in the ad to see information
  • Expand the view of the ad and zoom in/out 
  • Fill out a form embedded in the ad
  • Take a survey within the ad
  • Interact with different elements and play games in the ad

The process for using VPAID involves four steps:

  1. The video player requests an ad call[9] from the ad server.
  2. The server responds with the corresponding VAST XML file and the VPAID ad unit[10].
  3. The video player and video ad communicate back and forth, sharing properties throughout the user’s session.
  4. Both the video player and the ad unit send tracked impressions and activity data back to the ad servers.

VPAID 2.0 is the latest version and supports desktop, mobile devices, autoplay on Chrome for small players, and support of Flash, HTML5, and JS.

VPAID runs into a wall when it comes to in-app environments. Javascript is required when using VPAID since Flash is now officially dead. Some users refuse to adopt VPAID because it causes longer load times on mobile devices. It will also ignore inventory[11] when it doesn’t apply to the platform. Smart TVs and mobile devices don’t support all forms of interactivity.

What’s the Relationship Between VAST and VPAID?

The standard procedure is to use VAST as a base for basic service. Then when enhanced features are needed, VPAID is added on top to try to add interactivity. VPAID doesn’t replace VAST but is used to make the user experience richer.

What are the Differences Between VAST and VPAID?

Advertisers can pick and choose between the two depending on the functionality that they need to serve their ads.

  • VAST is used to establish communication between the video player and ad server, while VPAID bridges interactions between the video player and ad units.
  • VPAID is meant to interact with the video player, while VAST runs video ads on the player by coordinating with the ad server.
  • VAST supports all standard video formats, while VPAID requires compliant players to allow users to fully interact with ads.
  • VPAID can preload the ad before rendering the main video, while VAST won’t allow the ad to preload before the video.

VAST vs. VPAID: Is one superior to the other?

VAST lags behind VPAID, in that it struggles to resolve issues with API integration for scoring impressions in real time. Industry viewability standards are also a problem, creating a lack of trust in publishers.

VPAID’s issue is that it requires the .SWF format to read basic elements like images, GIFs, and interactive elements, unlike standard formats. At the same time, video players are often unable to read .SWF files. When this happens, VPAID will get overridden by VAST to make sure an ad is served. When this happens, the interactivity that VPAID was designed to facilitate is lost.


VAST and VPAID are both useful pieces of Ad Tech[12] bringing ads to consumers. These tools help standardize the industry and allow video players and publishers to serve ads from different servers without difficulty. Ads are also becoming more intimate and interactive while the number of platforms and devices that support ads is always increasing. As the demand for video increases, these tools make it possible for that content to generate revenue for the publishers who host it.  

1. Video Ad Serving Template [VAST] ( VAST ) Video Ad Serving Template is an industry-standard script that helps provide video players with information on which ads to display, how to display it, when and functions it should offer.
2. ad servers. The computer or group of computers responsible for the actual serving of creatives to websites, or for making decisions about what ads will serve. An ad server may also track clicks on ads and other data. Major publishers, networks and advertisers sometimes have their own ad servers. Well known ad servers include Google Ad Manager, Xandr, and OpenX.
3. impression. Impression is when a user views an ad on a page or when an ad is displayed on a webpage.
4. Ad Operations ( Ad Ops ) Ad Operations refers to processes and systems that support the sale and delivery of online advertising. More specifically this is the workflow processes and software systems that are used to sell, input, serve, target and report on the performance of online ads.
5. viewability. Viewability relates to the amount of time a user saw an ad.

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