Magnite VAST validator guide
Short answer: Magnite does not publish one VAST version for every impression. The ad unit selects the versions, and those protocols go out in the bid request. Validate the winning VAST document against that unit: duration, MIME type, wrappers, and the media file. Streaming ad serving runs through SpringServe.
Need a Magnite VAST validator?
Paste the tag or the bid's VAST. Check it against the ad unit that requested it.
Quick reference
| Role | Exchange. Streaming ad server is SpringServe. |
| Versions | Selected per ad unit and sent in the bid request |
| MIME type | video/mp4 at a minimum on the ad unit |
| Wrappers | Allowed by a supply setting, and unwrapped when that setting is on |
| Price in VAST | Pricing element on 3.x and later. An extension on 2.x. |
The ad unit declares the VAST it will take
Magnite's help glossary describes the VAST versions field as the versions that ad unit supports. More than one can be selected, and the selected protocols are sent to buyers in the bid request. The same glossary describes sampled winning documents by version, with 2.0, 3.x, and 4.x given as the examples, and by content type, with MP4, WebM, and JavaScript given as examples. Delivery on the asset is progressive, streaming, or download. The demand MIME list for the unit should include video/mp4 at a minimum, which the glossary calls the most widely compatible type.
Allow VAST Wrappers, set to yes, means that supply accepts a wrapper whose URI points at a VAST ad hosted elsewhere. Unwrap VAST, when enabled, unwraps wrapper responses from buyers. Emit Pricing writes the winning price into the VAST response: the standard Pricing element on 3.x and later, and an extension on 2.x. A tag that is valid in the abstract can still be the wrong shape for the unit that asked for it.
Bid responses have to match the request
Magnite's ad quality guidelines say a linear video bid, including companion units, must respect the limits in the bid request. That includes OpenRTB minduration and maxduration, and optional blocked attributes. Video ads must not loop or repeat unless the viewer triggers the loop. On the DV+ platform, buying a display impression and running a VAST video ad inside that banner is prohibited. In-banner video is a separate, case-by-case unit.
Creative review for streaming sits on SpringServe. Magnite describes BingeWatcher as the scanner that downloads a creative from an uploaded file, a programmatic bid, or a VAST tag, then stores metadata for language, context, and audio volume. A VAST tag with nothing playable behind it is the case that scanner, and the validator, are both meant to catch.
Pre-flight checklist
- The VAST version is one the ad unit selected.
- At least one media file is video/mp4 when that is the unit minimum.
- Duration sits inside the unit's minimum and maximum.
- A wrapper is present only if that supply allows wrappers.
- The document is a video response, not a VAST file stuffed into a display impression.