VAST vs VPAID: What Are They & How Do They Work?

Video advertising is expected to reach $180 billion in ad spend in 2022 and is one of the fastest growing areas of marketing. Spending is forecasted to continue to grow at a compound annual growth rate (CAGR) of more than 12% through 2027.

For publishers, this provides a significant opportunity to monetize a website, mobile site, and mobile app using video ad networks.

The growth in video consumption continues to accelerate for a variety of factors, including faster internet service. The rollout of 5G service nationwide will only fuel video use. Also, some 85% of Americans own a smartphone as a way to watch videos even outside of the home. Connected TV also provides an additional avenue for advertisers to use video ads.

For advertisers, it represents a way to engage consumers more dramatically. For publishers, it creates additional ad tech monetization options.

As technology has evolved, the Interactive Advertising Bureau (IAB) rallied the ad industry to develop standard video ad formats and follow best practices to provide a consistent user experience. That’s where VAST and VPAID come into play, helping standardize ad delivery across a multitude of video players and devices.

What is a Video Player Ad Interface (VPAID)?

VPAID stands for video player ad interface which is a script that video players to show ads, establishing a common interface that enables a rich interactive streaming experience. VPAID makes it easier to advertisers to develop creative that can work with different video players rather than having to create multiple versions for each player.

VPAID also records ad playback and user interactivity, so as a user interacts with a rich media ad inside a video ad unit, advertisers have access to the data generated.

VPAID supports HTML5 and JavaScript but is not currently supported by smart TVs. For mobile applications, Mobile Rich Media Aid Interface Definitions (MRAID) is an API also used for rich media ad serving to mobile devices.

One thing to note, however. VPAID was officially retired by the IAB Tech Lab and replaced by the Open Measurement Interface Definition (OMID) and Secure Interactive Media Interface Definition (SIMID), but still remains in use today. The IAB believes VPAID does not provide adequate transparency. VPAID was also used on a desktop in conjunction with Adobe Flash technology. As Flash was phased out due to security concerns, the replacement technologies evolved.

How VPAID Works

VPAID works similarly to other ad-serving methods. When the video player sends an ad call to the ad server, the server responds with a VAST XML file along with a compliant ad unit. The video player and ad unit continuously monitor for events initiated by users as part of the stream video ad experience.

Both the video ad unit and the video player track impressions and other user data, sending it back to the ad server.

User Interactivity with VPAID Ads

VPAID allows for multiple forms of interactivity, including allowing users to:

  • Expand ad views, such as zooming in or out
  • Click on different tabs within the ad to view additional information
  • Fill out embedded forms
  • Respond to in-ad surveys
  • Interact with other elements within the ad
  • Play games

VPAID is used on its own, but it is often embedded within VAST.

What is a Video Ad Serving Template (VAST)?

VAST, or Video Ad Serving Template, also allows video players to run ads via ad servers while letting publishers display ads the way they want on different sites and devices.

VAST was first developed by the IAB as an XML schema to enable in-stream video ads and address the compatibility issues between ad servers and video players to create an industry standard. Before VAST was adopted, advertisers would have to make sure their ad server was compatible with a publisher’s video player. If not, it would be unable to render the ad and instead have to substitute a different response.

How VAST Works

VAST also follows a familiar format to deliver ad performance.

The video player sends a request to the ad server and the server responds with the appropriate media files and tracking URLs. As ads play, the video player will send tracking pixels that contain data from the impressions.

While the earlier versions of VAST allow for basic functionality, they did not provide advanced features, VAST 2.0 and later VAST 3.0 added support for additional ad formats, including skippable ads. VAST 4.0 and VAST 4.1 added support for separate video and interactive files and server stitching with ad networks.

Despite these added functionalities, many publishers have still not adopted the latest versions of VAST.

Publisher Control Options with VAST

VAST gives publishers more control over compliant video players by configuring instructions for playback. For example, publishers can determine:

  • What ads should be shown
  • How ads are displayed
  • The length of ads
  • Where users go after the ad concludes with a CTA
  • Whether ads are skippable

Comparing VPAID and VAST

The main difference in comparing VPAID and VAST is that VPAID lets publishers serve interactive ads to users, while VAST doesn’t support this capability. Here are some of the other key differences involves in ad delivery.

Communicates between the video player and the ad server.Creates the interaction between the video player and ad server.
Runs video ads on the video player by working with the ad server.Interacts with the video server while ads are running in the video player in real time.
Exchanges data between the ad server and the video player without additional technology.Uses APIs integration to allow video players to accept more ads.
Does not allow preloading of ads before rendering.Enables video player to preload ad units before rendering.
Supports all standard video formats for ads.Also supports interactive formats for ads.

To use VAST, publishers must use a VAST-compliant video player. For VPAID, the video player must support VPAID creative elements for added interactivity.

While VAST can be used anywhere and enables more ad servers and video players, VPAID and MRAID work better for mobile environments with better measurement tools and functions like overlays contained within VPAID tags.

There is also a significant difference in reporting from the different formats. For example, VAST can capture:

  • Impressions
  • Clicks (including video companion clicks)
  • Video plays
  • Video first quartiles
  • Video completes
  • Pauses and mutes
  • Midpoints and fullscreen

VPAID can report on all of the same metrics that VAST can, but also provides more granular detail including:

  • Average display time
  • Average engagement/interaction time
  • Interaction rate
  • Interactive impressions
  • Rich media clicks and impressions
  • Total display time
  • Average view time
  • Video stops and replays
  • Video views
  • View unmutes

Pros and Cons of VPAID and VAST

There are pros and cons of using either format for serving video ads. Here are some of the key advantages and disadvantages.

VPAID Advantages

Adding interactive elements to online video ads provides additional monetization opportunities. Video players can display more types of ads. Publishers can charge more for the interactive elements while advertisers can get more immediate feedback on any activity.

Besides allowing for interactivity, VPAID also provides a more robust measurement of viewability metrics. Ad tags with VPAID provide more granular data for advertisers and publishers to gauge user behavior and ad performance.

VPAID also has security measures to help identify and mitigate fraudulent activity.

VPAID Disadvantages

VPAID also has some drawbacks as well.

VPAID has been known to slow down website load time due to latency in preloading. There can also be compatibility issues with some mobile video content, which can lead to the incorrect rendering of some ad formats—especially for mobile apps.

These disadvantages can impact programmatic ad spending, ad performance, and user experience.

VAST Advantages

VAST is a more common standard and more popular. This allows publishers to scale opportunities. Because VAST works cross-platform, it supports a broader coverage of devices. For example, VAST can support Connected TVs (CTVs).

The latest versions of VAST also handle ad delivery automatically with server-side ad insertion (SSAI), also known as ad stitching. This provides ad placements within a single stream delivered to a video player rather than switching to different servers when an ad call is made. As such, this helps provide a more seamless stream for users and bypasses most ad blockers since it doesn’t see the ad call within the video player.

VAST also supports what’s known as mezzanine video files. Mezzanine files are high-quality raw files that can be used to render videos at different compression rates, dynamically serving video and video ads at different quality depending on the device and device connectivity speeds.

VAST Disadvantages

Just like VPAID, however, VAST also has its drawbacks.

VAST is limited in interactive features and there can be latency when serving ads in video players that are unable to render the interactive elements. This results in longer load times. Also, older versions of VAST still in use, do not support the current viewability standards.

We also see examples of the inconsistent use of VAST creative identifiers across different ad platforms, which can negatively impact the viewing experience.


It’s estimated that video will account for 82% of all internet traffic in 2022. With the continuing growth in video consumption, including video ads, these forms of ad tech can provide additional ways for publishers to generate higher-paying ad rates.

VAST and VPAID provide advertisers and publishers with a common language to deliver ads to video players for consumption. While VAST tags have fewer compatibility issues, it lacks the granular reporting, tracking, and interactivity of VPAID tags.

Publishers should learn about the different ad formats along with their pros and cons to facilitate monetization for their digital properties.

When you work with the right ad network to monetize your site, like Newor Media, you get access to ad tech experts that know how to effectively manage ad formats and ad units to maximize your revenue. In fact, we help generate revenue for hundreds of industry-leading websites, handling more than 1.5 billion monthly ad impressions.

Our deeply established relationships with all major networks and supply-side platforms provide you with a diverse portfolio of advertisers, ensuring better ad fill rates and revenue optimizations.

Unlike some other ad networks, such as Google AdSense or Google Ad Manager, we also employ header bidding technology to show ad requests to multiple ad exchanges at the same time. This increases the competition for publisher advertising inventory, leading to higher cost per thousand (CPM) rates.

Contact the Newor Media team today to get started and let us show you how we can increase your ad revenue.

Wondering how much money you could be earning with Newor Media? Try our free website earnings calculator to find out.

Lauren Aloia

Senior Account Manager, Publisher Development: Newor Media

Lauren is an ad tech expert with a wealth of experience spanning product development, ad operations, and data analysis. She currently works with Newor Media publishers to implement yield optimization strategies that maximize revenue from their programmatic inventory.