VASTlint

VAST macros / Ad and pod

[ADSERVINGID] VAST macro

Short answer: The unique ad-serving identifier shared across the supply chain. Introduced in VAST 4.1.

What it means

Resolves to the AdServingId from the InLine ad: a single identifier that ties together logs from every party that handled the impression, simplifying discrepancy debugging.

Example value

After the player substitutes the macro, [ADSERVINGID] becomes something like:

ssp-a1b2c3-20260627

Where it is valid

Impression, tracking, error, and click URLs.

Macros are case-sensitive and substituted only inside URL fields. A macro written in the wrong case, or placed where it has no defined value, is sent to the server as literal text instead of a value.

Using it in a tag

<Impression><![CDATA[https://t.example.com/i?val=[ADSERVINGID]&cb=[CACHEBUSTING]]]></Impression>

VAST XML fragment only. This excerpt belongs inside a complete VAST document, so standalone validation will fail until it is wrapped in a full <VAST>response.

Related vastlint rules

Related macros

Validate your macros

vastlint flags unknown, mis-cased, deprecated, out-of-context, and unencoded macros in any tracking, click, error, impression, or media URL:

# CLI: exits non-zero on errors, ideal for pipelines
vastlint check creative.xml

Use the right tool for this failure

If you already have the resolved XML, run a pure spec check. If you only have a live tag URL, test that endpoint first. If the failure happens in the wrapper chain, inspect each hop.

Validate this XML →Test this live URL →Inspect this wrapper chain →

Further reading