Use the Display & Video 360 REST API firstAndThirdPartyAudiences resource to create a new first-party audience; set the audienceType to FIRST_PARTY and define the audienceSource (e.g., YOUTUBE, GOOGLE_ANALYTICS, or PIXEL).
For pixel-based audiences, reference the Floodlight activity tag or Google tag that fires on the relevant conversion or page-visit event.
Set the membership duration (membershipDurationDays) to specify how long a user remains in the audience after qualifying; the maximum supported duration is 540 days.
Link the audience to a line item's audienceTargetingConfig by including the audience segment ID in the includedFirstAndThirdPartyAudienceGroups field.
Allow 24–48 hours for the audience to populate before expecting targeting to take effect; newly created segments start with zero members and will not serve until the minimum size threshold is reached.
Use the audienceGroups structure to combine multiple segments with AND or OR logic; AND (intersection) logic requires all segments to be in the same group, while OR (union) logic uses separate groups.
Known gotchas
DV360 first-party audiences built from Floodlight tags share the same data as Google Ads remarketing lists only when the advertiser's Floodlight is linked to a Google Ads account; without this link, the audiences are not available cross-platform.
Setting membership duration to the maximum (540 days) does not guarantee users stay for that period; users who clear cookies or use different devices may exit the audience earlier, especially on browsers with ITP restrictions.
The minimum audience size required before a segment is eligible for targeting is not publicly documented and varies by audience type; plan for a ramp-up period where a new segment cannot be activated even if correctly configured.
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