VAST Tag Tester

Test VAST tags online by entering a VAST URL or XML response. Preview video ads, inspect tracking information and investigate problems before sending the tag into production.

What is VAST?

Video Ad Serving Template (VAST) is an IAB standard that enables video players to communicate with ad servers. It provides a structured XML response containing the media file, tracking pixels, and clickthrough instructions needed to render a video ad.

How VAST testing works

When you enter a VAST URL, our tool requests the XML from the ad server, parses the response, and simulates video ad playback. It tracks the progress of the video and logs all tracking events just like a real video player would.

How to test a VAST URL

Paste the VAST endpoint into the tester above and click render. The tool will fetch the response and load the video. Ensure your endpoint allows cross-origin requests (CORS) if you are testing locally, though our server proxy handles standard requests.

How to test VAST XML

You can paste raw VAST XML directly into the tester. This is helpful if you want to test a hardcoded response or bypass network requests. The tool will parse the XML exactly as it would a remote URL.

Common VAST problems

VAST tags often fail due to structural issues in the XML, missing media files, or missing tracking events. Our tester highlights these problems so you can fix them. If you suspect structural errors, you can also use our VAST validator to inspect the XML closely.

Tracking events

Check the console logs to see which tracking events are firing. The tool logs impressions, quartiles (25%, 50%, 75%), complete, and pause events, helping you verify that your tracking pixels are correctly implemented.

Media files and video ad playback

The tester extracts the available media files from the VAST response and attempts to play the most appropriate video format. If the video fails to play, check the media file URL and verify that the video format is supported by standard browsers.

Clickthrough URLs

Test the click behavior of the video ad. The tester displays the destination URL provided in the VAST response, allowing you to ensure the user is directed to the correct landing page upon clicking the ad.

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