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    SDA

    Seller Defined Audiences

    cookieless

    IAB Tech Lab cookieless targeting framework where publishers classify first-party audiences using IAB Audience Taxonomy IDs and pass them in OpenRTB bid requests via segtax=4.

    What is SDA?

    Seller Defined Audiences (SDA) is an IAB Tech Lab standard (v1.1, 2022) for cookieless audience targeting. Publishers (sellers) classify their authenticated and non-authenticated first-party audiences using the IAB Audience Taxonomy and pass standardized cohort IDs to buyers inside the OpenRTB bid request.

    It is the industry's answer to third-party cookie deprecation: instead of buyers fingerprinting users across the open web, sellers describe their own audiences in a shared, privacy-safe vocabulary.

    How it works

    SDA cohorts travel inside bidrequest.user.data[] with segtax=4 (the registered taxonomy ID for IAB Audience Taxonomy 1.1):

    "user": {
  "data": [{
    "name": "publisher.com",
    "ext": { "segtax": 4 },
    "segment": [
      { "id": "771" },  // Auto Enthusiasts
      { "id": "496" }   // Luxury Travel Intenders
    ]
  }]
}

    The DSP receives the cohort IDs, looks them up against the public taxonomy, and bids accordingly — without ever receiving a user identifier.

    Why it matters

    • Cookieless-native: works in Safari, Firefox, and post-cookie Chrome
    • Standardized: all SDA-compliant SSPs/DSPs speak the same audience vocabulary
    • Privacy-forward: cohorts are aggregated and passed without PII; complementary to TCF and GPP consent signals
    • Publisher-controlled: sellers monetize their first-party data without leaking it to ad-tech intermediaries

    Relationship to consent signals

    SDA cohorts are always gated by consent. A bid request must carry valid TCF (EEA/UK) or GPP (US state-level) signals before a DSP can act on the cohort IDs. SDA does not replace consent — it operates on top of it.

    Relationship to UCP

    While UCP (Unified Context Protocol) describes page-level context, SDA describes audience cohorts. The two are complementary signals in the same bid request.

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