VAST Tag Validator
Parse, inspect, and validate VAST 2.0 through 4.2 video ad tags. Every MediaFile URL fetched, every tracking pixel tested, every companion ad inspected — all in seconds, free, with no signup.
Validate a VAST Tag →What the VAST Validator checks
VAST version compliance
Detects 2.0, 3.0, 4.0, 4.1, 4.2 and flags deprecated or non-compliant elements for each.
MediaFile validation
Fetches each MediaFile URL, verifies HTTP status, MIME type, bitrate declaration, and SSL.
Tracking pixel tests
Impression, quartile (start/first/mid/third/complete), click, and error pixels all reached and verified.
Companion ads
Companion creative references parsed, dimensions validated, and StaticResource / IFrameResource / HTMLResource checked.
Wrapper chains
Follows VAST wrappers up to standard depth, detects redirect loops, and reports chain hop count.
OMID / VPAID signals
Detects Open Measurement verification scripts and VPAID JS interfaces in the ad response.
How it works
Paste your VAST tag URL or XML
Works with ad server VAST URLs, inline VAST XML, or wrapped VAST chains.
Tag is parsed and fetched
We parse every element, then fetch MediaFile URLs and fire tracking pixels in a sandboxed environment.
Full report in seconds
Get VAST version, duration, MediaFile count, pixel inventory, wrapper depth, and every issue we detected.
Frequently asked questions
Which VAST versions do you support?
All major versions — VAST 2.0, 3.0, 4.0, 4.1, and 4.2. Version-specific compliance rules are applied per tag.
Does it validate MediaFile URLs?
Yes — every MediaFile URL is fetched and checked for HTTP status, MIME type, and SSL compliance. Broken MediaFiles are flagged critical.
Are tracking pixels tested?
Yes — impression, quartile, click, and companion pixels are all validated for reachability and SSL compliance.