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This concept operates at the Dsp layer of the programmatic supply chain.
Targeting · LAL

Lookalike Modeling

Lookalike modeling finds new prospects who resemble a brand's best existing customers, expanding reach by identifying users with similar attributes to a seed audience.

Updated 2025-07-06 Author Luc Dumont Reading time ~4 min

Key takeaways

  • Lookalike modeling expands a seed audience to similar new users.
  • The quality of the seed audience largely determines the result.
  • First-party seeds have become the strongest input after cookie loss.
  • It powers prospecting and scaled acquisition in DSPs and walled gardens.

Seeds and similarity

A lookalike model starts with a seed "” often a brand's best customers or converters "” and identifies other users who share their attributes and behaviors. This lets advertisers move beyond re-reaching known users to prospecting new ones who statistically resemble proven value.

Why the seed matters most

A lookalike is only as good as its seed. A tight, high-value first-party seed produces a sharper, more valuable audience than a broad or noisy one. As first-party data became the durable asset post-cookie, first-party seeds became the backbone of quality lookalike modeling.

At a glance
InputA seed audience
OutputSimilar new prospects
Key driverSeed quality
Use caseProspecting / scaled acquisition

Frequently asked questions

What is a seed audience in lookalike modeling?

The seed is the source group "” often best customers or recent converters "” that the model uses as a template to find similar new users.

Why is lookalike quality tied to first-party data?

Because a precise, owned first-party seed produces sharper models than broad third-party segments, and first-party data is the most durable input after cookie deprecation.