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VAST Tag Validator

VAST Tag Validator

20 FREE Quality Assurance tests for VAST Video Ads

Enter your VAST URL to start the scan.
Like Google VAST Inspector
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Audio Sample Rate

Common rates are 44.1 kHz and 48 kHz. Lower rates may indicate poor audio quality.

Audio Codec

The algorithm used to compress the audio track. A common codec is AAC for MP3.

Audio Loudness

Comply with EU EBU R128 or US ATSC/85 to make sure the audio loudness level is in the recommended range of -23 LUFS ± 2 LU.

Aspect Ratio

The ratio between the width and height of the video. Common aspect ratios are 16:9 and 4:3.

Video Resolution

Determines the quality of the video. Common resolutions are 1920x1080 and 1280x720.


The length of the video in seconds. For pre-rolls, commonly accepted durations are 6s, 15s and 30s.

Bit rate

The amount of bits the video holds per second. A higher bitrate translates to a higher quality.

Frame rate

The amount of video frames per second. Common frame rates are 24 fps, 25 fps and 30 fps.

File Size

The total file size of the video in bytes.

Container Format

The container format holds video, audio and meta-data information. A common format is MP4, which is supported by almost all devices.

Video Codec

The algorithm uses to compress the videos. A common codec is H.264 for MP4 files. Note that the newer H.265 has poor browser support.

MOOV Atom Position

For streaming videos, the MOOV atom (which acts like a Table of Contents) should be located at the beginning of the file. If not, the entire video has to be downloaded before it can start playing.

Delivery Type

Videos can be delivered either progressive or interlaced. Most technologies only accept progressive deliveries.

VAST Spec Compliancy

This test makes sure the VAST tag has all required parameters as per IAB's VAST specification. Non-valid VAST tags may prevent the video from loading.

VAST Spec Discrepancy

This test detects if the VAST tag holds incorrect information about the video. For example, if it 'fakes' a higher bitrate than the actual video.

VAST Version

The VAST version as reported by the tag. You can configure the scan to accept only certain versions.

Download Speed

Slow servers may cause the video to stall while buffering. This test measures if the download speed is sufficient to stream the video without interruption.

Skip Detection

This test makes sure that the video ad can be skipped.


Detects if all assets use secure URLs (https).

CORS Header Check

The VAST tag should have a valid CORS Header. Without CORS, the video player wouldn't be able to fetch the tag via XHR.