How do I validate a Celtra VAST tag?

Generate the tag for the placement, then validate that output. Celtra's tag generator writes the VAST version and the encoding presets from the selected tag template into the Universal VAST tag.

Where does Celtra set the VAST version?

For Universal VAST videos, the tag generator has a VAST version choice in the Vast Unit section. The version on the generated tag is the one to validate.

Does Celtra publish one bitrate ladder for every VAST tag?

No. Encoding settings, including minimum bitrate thresholds, are stored on the tag template. Default settings use Celtra's standard encoding. Custom settings add presets defined on that template. Presets are edited on the template, not in the tag generator.

Celtra VAST validator guide

Short answer: Celtra generates a Universal VAST tag per placement. You pick the VAST version in the tag generator, and the encoding presets come from the tag template selected for that placement. Validate the generated tag. The source file you uploaded is not the document a player will parse.

Need a Celtra VAST validator?

Export or copy the generated tag for the placement, then run that XML. Use the tester when the generator gave you a URL.

Validate the generated tag →Test the tag URL →

Quick reference

Role	Creative platform that generates tags for a placement
VAST version	Chosen in the tag generator, Vast Unit section, for Universal VAST videos
Encoding	Applied from the selected tag template. Default presets, or default plus custom presets.
What the presets control	How the VAST video is encoded, including minimum bitrate thresholds for the placement
Where presets are edited	Tag template settings. The generator applies them and does not edit them.

What the tag generator writes

Celtra's tag generator is the step that picks tags for a creative that already has a placement. Publishers, ad networks, and SSPs do not share one tag shape, so the generator is tied to a tag template. For Universal VAST video, the Vast Unit section is where you choose the VAST version. That choice is what lands on the root version of the generated document.

Encoding settings travel with the template. Celtra describes them as the control for how the VAST video creative is encoded, including minimum bitrate thresholds, so the generated tag meets the placement. Selecting the template applies the presets saved on it. Default encoding uses Celtra's standard video encoding. Custom encoding adds the preset list defined on that template. If the custom option is missing after you select a template, that template has no custom presets.

Presets are created on the tag template, not in the generator. Changing bitrate or rendition settings means editing the template and generating the tag again. Validating an older export after a template edit checks the previous file.

Validate the generated tag

Generate the Universal VAST tag for the placement you will traffic.
Confirm the version in the Vast Unit section is the version you meant to ship.
Paste the XML into the validator. If you received a URL, fetch it in the tester first.
Read the MediaFile entries. They should reflect the template's presets, including the minimum bitrate the placement asked for.
Regenerate after any template change, and validate the new output.

Pre-flight checklist

The tag you test is the generator output for this placement.
The root version matches the Vast Unit selection.
Media files and bitrates match the template presets, default or custom.
Media and tracking URLs in the generated tag use HTTPS.
The XML passes the validator.

What this guide does not assume

Celtra's tag generator article does not publish a fixed list of VAST versions, a wrapper-depth cap, or one codec ladder for every placement. The version is the one you select, and the renditions are the presets on that template. A display-component upload spec is a different document from the Universal VAST output. Check the generated tag.

Sources

Celtra: Using the Tag Generator