Vast

July 15, 2026 · View on GitHub

CI Coverage

:star: VAST Ad generator and parser library on GoLang. XML / JSON.

The struct model targets VAST 4.3 (the latest version) and is backwards compatible with VAST 2.0, 3.0, 4.0, 4.1 and 4.2.

VAST versions

VersionReleasedStatusHighlights
1.02008DeprecatedOriginal linear video ad template.
2.02009SupportedMultiple media files, companion & non-linear ads, tracking events.
3.02012SupportedAd pods (sequenced ads), skippable ads, industry icons (AdChoices), wrapper improvements, error macros.
4.02016SupportedSeparation of media files from interactive/VPAID code, Mezzanine for server-side ad stitching (SSAI), viewability, UniversalAdId, Category.
4.12018SupportedVPAID/Flash deprecation, InteractiveCreativeFile + SIMID/OMID, audio ads (adType, DAAST merged in), AdServingId, Expires, BlockedAdCategories.
4.22019SupportedMultiple UniversalAdId, IconClickFallbackImages, closed-caption files, ClosedCaptionFiles, verification refinements.
4.32022Supported (default)Macros managed on GitHub, [PLAYBACKMETHODS]=7 (continuous/binge play), inline data URI support for InteractiveCreativeFile, CTV-focused clarifications.
CTV Addendum2024N/A (backwards-compatible extension)ACIF ad registration, DSA compliance icons, high-resolution creatives — layered on top of any VAST 4.x version.

Specs

Installation

go get -u github.com/haxqer/vast

Quick Start

package main

import (
	"encoding/xml"
	"fmt"
	"time"

	. "github.com/haxqer/vast"
)

func main() {
	v := VAST{
		Version: "4.3",
		XMLNS:   "http://www.iab.com/VAST",
		Ads: []Ad{{
			ID:     "123",
			AdType: "video",
			Type:   "front",
			InLine: &InLine{
				AdSystem:    &AdSystem{Name: "DSP", Version: "4.3"},
				AdServingId: "DSP-123-request-456",
				AdTitle:     PlainString{CDATA: "adTitle"},
				Impressions: []Impression{
					{ID: "11111", URI: "http://impressionv1.track.com"},
					{ID: "11112", URI: "http://impressionv2.track.com"},
				},
				Creatives: []Creative{{
					ID: "987",
					UniversalAdID: &[]UniversalAdID{
						{IDRegistry: "Ad-ID", ID: "8465"},
					},
					Linear: &Linear{
						Duration: Duration(15 * time.Second),
						TrackingEvents: &TrackingEvents{Tracking: []Tracking{
							{Event: EventTypeStart, URI: "http://track.xxx.com/q/start?xx"},
							{Event: EventTypeFirstQuartile, URI: "http://track.xxx.com/q/firstQuartile?xx"},
							{Event: EventTypeMidpoint, URI: "http://track.xxx.com/q/midpoint?xx"},
							{Event: EventTypeThirdQuartile, URI: "http://track.xxx.com/q/thirdQuartile?xx"},
							{Event: EventTypeComplete, URI: "http://track.xxx.com/q/complete?xx"},
						}},
						MediaFiles: &MediaFiles{MediaFile: []MediaFile{{
							Delivery: "progressive",
							Type:     "video/mp4",
							Width:    1024,
							Height:   576,
							URI:      "http://mp4.res.xxx.com/new_video/2020/01/14/1485/335928CBA9D02E95E63ED9F4D45DF6DF_20200114_1_1_1051.mp4",
						}}},
					},
				}},
			},
		}},
	}
	vastXMLText, _ := xml.Marshal(v)
	fmt.Printf("%s", vastXMLText)
}

Result Demo

<VAST version="4.3" xmlns="http://www.iab.com/VAST">
    <Ad id="123" adType="video" type="front">
        <InLine>
            <AdSystem version="4.3">DSP</AdSystem>
            <Impression id="11111"><![CDATA[http://impressionv1.track.com]]></Impression>
            <Impression id="11112"><![CDATA[http://impressionv2.track.com]]></Impression>
            <AdServingId>DSP-123-request-456</AdServingId>
            <AdTitle>adTitle</AdTitle>
            <Creatives>
                <Creative id="987">
                    <Linear>
                        <TrackingEvents>
                            <Tracking event="start"><![CDATA[http://track.xxx.com/q/start?xx]]></Tracking>
                            <Tracking event="firstQuartile"><![CDATA[http://track.xxx.com/q/firstQuartile?xx]]></Tracking>
                            <Tracking event="midpoint"><![CDATA[http://track.xxx.com/q/midpoint?xx]]></Tracking>
                            <Tracking event="thirdQuartile"><![CDATA[http://track.xxx.com/q/thirdQuartile?xx]]></Tracking>
                            <Tracking event="complete"><![CDATA[http://track.xxx.com/q/complete?xx]]></Tracking>
                        </TrackingEvents>
                        <Duration>00:00:15</Duration>
                        <MediaFiles>
                            <MediaFile delivery="progressive" type="video/mp4" width="1024" height="576"><![CDATA[http://mp4.res.xxx.com/new_video/2020/01/14/1485/335928CBA9D02E95E63ED9F4D45DF6DF_20200114_1_1_1051.mp4]]></MediaFile>
                        </MediaFiles>
                    </Linear>
                    <UniversalAdId idRegistry="Ad-ID">8465</UniversalAdId>
                </Creative>
            </Creatives>
        </InLine>
    </Ad>
</VAST>

Model fidelity

Companion, NonLinear, and Icon expose the unbounded VAST resource elements through HTMLResources, IFrameResources, and StaticResources. The older singular fields remain available as compatibility aliases for the first resource.

Optional XML booleans retain their existing bool fields. When an explicit false must be distinguished from an omitted attribute, set the matching ...Set field (for example, VariableDurationSet or ScalableSet). XML parsing sets these presence fields automatically, so XML and JSON round trips remain lossless.

Testing and coverage

The test suite currently provides 97.4% statement coverage. Run the same race-enabled coverage check used by CI with:

go test -race -coverprofile=coverage.out -covermode=atomic ./...
go tool cover -func=coverage.out

Thanks