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.
Ad Me In
Enter Your VAST Tag URL to validate
VAST Tag Examples
AdMeIn Icon ExampleVAST LinearVAST VPAID Example TagVPAID InteractiveAdMeIn Single Wrapper ExampleVAST WrapperAdMeIn Multi Ad ExampleVMAP Multi-AdAdMeIn Companion Ads ExampleVAST CompanionGoogle Multi Ad ExampleGoogle IMAGoogle SIMID ExampleSIMID InteractiveAdform VAST SampleProduction ExampleInnovid ExampleThird-Party Server
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: AdMeIn Single Wrapper Example
VAST wrapper that redirects to another VAST tag. Tests wrapper chain resolution and tracking event aggregation.Learn more about this topic and its features on our guide page here.
To 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.
VAST 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 vast version
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 media files
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.
Duration
Validates that the ad duration is specified and reasonable.
We recommend a duration of 15–30 seconds for most ads.
Why we test duration
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 tracking events
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 click tracking
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 impression tracking
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 companion ads
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 ad system
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 api framework
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 ad sequence
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 sequence timing
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 vmap version
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 ad breaks
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 ad break timing
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 vast references
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.
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:
- AdSystem, AdTitle, ImpressionFailed example:
- MediaFile (missing or invalid URL)Warning or Optional example:
- Companion Ads (optional)Tip: Click on each result for more details and suggestions on how to fix any issues that may have been detected.
Visit our help center for more information:
- Paste a VAST tag URL into the url input field.
- Click "Validate" to check for errors and preview your ad.
- Review the results to fix any issues that arise.
Always review your VAST tags in multiple VAST testers to ensure compatibility.
Helpful VAST guides.
Other tools for video ad testing.
Try our new VAST tag generator playground to generate and test VAST tags examples.
Frequently Asked Questions
What is a VAST tester?
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.
How can I test interactive video ads?
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.
What is video ad pod?
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.
How can I test a multi-VAST tag or VMAP tags?
You can test a multi-VAST tag or VMAP tags by using our VAST tester, which supports both formats and provides detailed validation results.
How do I test a VAST tag online?
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.
What errors can a VAST tester detect?
Our tester checks for XML validation issues, missing creatives, wrapper problems, tracking errors, and more.
Is this VAST tester free?
Yes, our VAST tester is completely free to use.