VAST Tag Tester
Validate VAST XML, wrapper chains and tracking URLs
About VAST Tag Tester
VAST Tag Tester is a free diagnostic tool for ad operations teams and video ad developers who need to check the XML an ad server returns before a tag goes live. You can submit a VAST URL, paste raw XML or upload a file, and the tool parses the response on its server, follows wrapper redirects up to five hops, and reports validation findings.
The report separates structural problems from wrapper, media and tracking configuration issues. It lists impression, click, error and progress-event URLs, groups recognizable vendors, flags placeholders with unresolved macros, and shows MediaFile details such as delivery type, MIME type, bitrate and dimensions. An error code reference helps explain standard VAST codes such as wrapper limits and no-ad responses.
The tool supports VAST 2.0 through 4.3 and needs no account, API key or extension. Its results are guidance rather than a guarantee, so the site recommends confirming behavior in the target player or SDK. Users are advised to remove credentials and sensitive parameters from inputs before testing.
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