VAST Testing
What is VAST & How to Test VAST Tags
Learn about VAST, how to test VAST tags, and best practices for video ad creatives. Explore our guides to ensure your video ads are compliant and error-free.
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Enter Your VAST Tag URL to validate
VAST Tag Examples
Explore our Ad Tag Example Gallery Library. A collection of ad tag examples with detailed descriptions, code snippets and live demos.
How Our Online VAST Tester Works
- Paste your VAST tag URL into the input field.
- Click the "Validate" button to start the validation process.
- Review the validation results and fix any issues using the provided feedback.
What is a VAST Tester?
A VAST tester is a tool that loads your VAST XML ad tag and simulates how a video player would interpret it. Instead of guessing whether your tags will deliver correctly, you can test them online and spot issues before launch.
VAST Video player - Ad Preview and Inspector
Viewing VAST Example Tag: Adserver Online Example
Adserver Online ad server VAST tag example. Tests third-party ad server integration and tracking for CTV, OTT and OLV compatibilities.Ad Tag Source by
Features included in this example:
- Tracking and analytics
- Cross-device compatibility
- Multiple video formats supported
- CTV/OTT
- OLV
- VAST Inline linear ad
- Video delivery MP4
- Companion banner
- VAST version 3.0
This is an example of Adserver Online's VAST tag service. A real world implementation of a VAST video ad served through Adserver Online's platform. It features a basic Ad made for [Bounty Paper Towels](https://bountytowels.com/en-us/shop-products) including tracking capabilities, click through functionality and a companion banner. The ad is designed to be compatible across multiple devices, including desktop, mobile, and connected TV platforms. With a duration of 15 seconds, this ad provides a great place to learn the basics of VAST ad tags.
View more details about this AdTo test this example, click the Validate and test Ad button
Click here to view the example tag used.
VAST Tag Preview & Validator
Once you paste your VAST tag URL and click Validate, your VAST tag preview will appear here. Our VAST online validator instantly loads your ad response, showing a live video ad playback, media file details, and tracking events.
Video ad previews are powered by the Google IMA SDK.
Our VAST tester helps you:
- Debug and troubleshoot VAST errors
- Preview video ads in real-time
- Inspect media assets and tracking pixels
- Verify compliance with VAST standards
- How to fix common VAST errors detected during validation
By running your tags through the preview, you can be confident your video ads will deliver correctly before launching campaigns.
Looking to test Html5 ad tags?Try out the AdMeIn ad tag validator.
Test a tag nowVAST Validation Results
What We Test For
When you run a test in our VAST Tag Tester, we check your VAST or VMAP tag for the following common issues and best practices
VAST Version
Checks if the VAST version is supported and valid.We currently support all versions of VAST: 2.0, 3.0, 4.0, 4.1, 4.2
Why we test this:
Different VAST versions introduce new elements and deprecate old ones. Testing ensures the XML structure and features align with the supported version, preventing compatibility issues with players and ad servers.
Media Files
Ensures media files are present and properly formatted.We support various media file types including MP4, WebM, and Ogg.
Why we test this:
Media files are the core of any video ad. Testing ensures the file type, codec, bitrate, and delivery method meet player compatibility standards, preventing playback errors and poor viewing experiences.
Ad Duration
Validates that the ad duration is specified and reasonable.We recommend a duration of 15–30 seconds for most ads.
Why we test this:
A defined duration helps players allocate correct playback time and manage ad pods efficiently. Missing or invalid durations can cause playback interruptions or failed ad requests.
Tracking Events
Checks for required tracking events and their correctness.We support various tracking events including start, firstQuartile, midpoint, and complete.
Why we test this:
Tracking events provide essential performance metrics such as completion rate and viewer engagement. Missing or incorrect events lead to inaccurate analytics and reporting discrepancies.
Click Tracking
Verifies click tracking URLs are present.Click tracking is essential for measuring ad engagement.
Why we test this:
Click tracking URLs record user interactions with the ad. Without proper click tracking, advertisers lose insight into engagement and campaign effectiveness, affecting billing and performance analysis.
Impression Tracking
Ensures impression tracking is implemented.Impression tracking helps monitor ad views and performance.
Why we test this:
Impression tracking confirms when an ad has been served and viewed. It’s a critical metric for verifying delivery, preventing fraud, and ensuring accurate reporting to advertisers and publishers.
Companion Ads
Checks for valid companion ads if present.Companion ads enhance user engagement alongside video ads.
Why we test this:
Companion ads extend the ad experience across formats and screens. Testing ensures they are correctly linked and formatted, avoiding display issues and maintaining creative consistency.
Ad System
Validates the AdSystem element.AdSystem identifies the ad server or system that provided the ad.
Why we test this:
The AdSystem element provides transparency about the ad’s origin and helps with troubleshooting, analytics, and attribution across ad delivery chains.
API Framework
Checks for correct API framework usage.Common API frameworks include VPAID and SIMID.
Why we test this:
The API framework defines how the creative interacts with the player. Testing ensures compatibility with supported frameworks, avoiding execution failures or blocked interactions on CTV and desktop environments.
Ad Sequence
Validates ad pod sequence numbers (for sequential ads).Ensures ad sequence numbers are unique and properly ordered.
Why we test this:
Ad sequence testing guarantees that ads play in the intended order within a pod, ensuring storytelling, pacing, and compliance with campaign delivery requirements.
Sequence Timing
Checks total duration and timing of ad pods.Ensures total ad pod duration is within acceptable limits.
Why we test this:
Proper sequence timing maintains a smooth viewing experience. Overly long or poorly timed ad pods can cause user drop-off, violate publisher limits, or fail ad insertion rules.
VMAP Version
Checks VMAP version (for VMAP tags).We currently support VMAP 1.0.
Why we test this:
VMAP defines how ad breaks are scheduled in long-form content. Testing ensures compliance with supported VMAP standards, preventing scheduling conflicts or playback errors in ad stitching systems.
Ad Breaks
Validates ad breaks in VMAP.Ensures ad breaks are properly defined and formatted.
Why we test this:
Ad breaks determine when and how ads appear during content playback. Validating them ensures correct structure, preventing missing mid-rolls or misaligned ad placements.
Ad Break Timing
Checks timing of ad breaks in VMAP.Ad breaks should be scheduled at appropriate intervals.
Why we test this:
Properly timed ad breaks maintain viewer engagement and balance monetization with user experience. Poorly spaced breaks can lead to audience frustration or reduced ad revenue.
VAST References
Ensures VMAP ad breaks reference valid VAST tags.We currently support VAST 2.0, 3.0, and 4.0+
Why we test this:
Each ad break in a VMAP should point to a valid VAST tag. Testing ensures referenced VAST URLs are accessible and well-formed, avoiding empty breaks or failed ad requests during playback.
Learning and Resources
Results example
After you validate your VAST tag, you'll see a detailed breakdown of each section of your VAST XML. The results show which parts passed, which failed, and how to fix any issues found.
Passed example:
Passed results will be highlighted in green and indicate that the corresponding section of your VAST XML is correctly formatted and compliant with VAST specifications.
Failed example:
Failed results will be highlighted in red and indicate that there are issues with the corresponding section of your VAST XML that need to be addressed.
Warning or Optional example:
Warnings or optional results will be highlighted in gray and indicate that while the corresponding section of your VAST XML is not critical, it may still require attention for optimal performance or self reference.
VAST Tag Generator
Streamline training, debugging, and QA by letting you generate and validate tags all in one place.
VAST Tag Form Builder
Our VAST Tag Generator is a simple, interactive form tool that helps you build custom VAST URLs directly inside the VAST Tag Tester. Open the modal, choose your parameters, and instantly create a clean VAST tag you can test on the spot.
Learn about VAST XML and Structure
Designed for learning and experimentation, this VAST Tag Builder shows how each field affects the final ad request, making it ideal for developers, ad-ops teams, and anyone wanting to understand VAST more clearly.
Other tools for video ad testing
Looking to validate video ad creatives for compliance and performance issues? Try our Video Validator tool to ensure your video ads meet industry standards.
Video Validator Tool
The AdMeIn Video Validator tool allows you to test video ad creative's asset for compliance and performance issues, ensuring your ads meet industry standards before going live.
The Video Validator helps you identify potential issues that could affect your ad's delivery and effectiveness.
- Check video format compatibility
- Analyze bitrate and resolution
- Ensure proper encoding settings
- Plus much more
VAST Validators and references
Always review your VAST tags in multiple VAST testers to ensure compatibility. Here are some recommended options
Google IMA VAST tester and inspector
Validate VAST tags using Google's official IMA VAST tester and inspector tool.Google IMA VAST tester and inspector
IAB guides and best practices
Refer to IAB's official guides and best practices for VAST compliance.IAB guides and best practices
AdMeIn Help Center
Visit the AdMeIn Help Center for comprehensive guides and support.AdMeIn Help Center
Related Article
Read guide
Frequently Asked Questions
- A VAST tester is a tool that lets you simulate how a video player would process your VAST XML ad tag, helping you validate creatives, tracking, and delivery.
- You can test interactive video ads using our video ad tester, which simulates the ad playback environment to ensure your interactive video creatives function correctly. Interactive video ads are often VPAID, SIMID and SHARC formats.
- A video ad pod is a group of video ads or a collection of ads that are played sequentially within a single ad break. This allows for multiple ads to be shown to the viewer in a single viewing session. Pods are generally scheduled to play at the beginning (pre-roll), in the middle (mid-roll), or at the end (post-roll) of the content.
- You can test a multi-VAST tag or VMAP tags by using our VAST tester, which supports both formats and provides detailed validation results.
- Simply paste your VAST tag URL into our VAST tester online, and it will load the ad response, show the video playback, and report any issues.
- Our tester checks for XML validation issues, missing creatives, wrapper problems, tracking errors, and more.
- Yes, our VAST tester is completely free to use.