Delivering Ad Relevance Without Third-Party Cookies

As the advertising industry faces the inevitable shift away from third-party cookies, the focus is increasingly on innovative, privacy-compliant solutions. This blog post explores Amazon Ads’ groundbreaking strategies to deliver relevant advertisements without relying on third-party cookies, leveraging advanced modeling techniques to maintain ad effectiveness and respect user privacy.

The Transition from Third-Party Cookies

For the past seven years, the advertising industry has been preparing for the shift away from third-party cookies. This transition is not merely a technical change but a response to evolving privacy regulations and consumer demands for more control and transparency online. Significant legislative milestones and privacy initiatives from major tech companies have accelerated this shift.

Amazon Ads’ Approach: First-Party Signals and Modeled Audiences

At the heart of Amazon Ads’ strategy is the use of first-party signals generated from the vast ecosystem of Amazon services, including Alexa, Prime Video, and These high-quality signals offer deep insights into consumer preferences and behaviors. Amazon Ads leverages these signals to create in-market and lifestyle audience segments, which are further refined through machine learning models to maintain relevance even when ad IDs are unavailable.

Technical Insights: Model Architecture and Audience Clustering

The core of Amazon Ads’ technical approach involves sophisticated audience modeling. This process includes:

  • Model Architecture: Utilizing deep neural models to classify new observations based on signal-focused attributes, Amazon Ads’ models predict the relevance of impression opportunities to specific audiences. This multi-label classification approach allows the model to learn patterns among correlated audience memberships, enhancing scalability and precision.
  • Audience Clustering and Mapping: Using tools like Sentence-BERT and HDBSCAN, Amazon Ads clusters related audiences based on their interactions and descriptions. This clustering helps in cross-learning between markets, ensuring that insights from one country can be applied to others, optimizing the modeling process.
  • Hierarchical Thresholding: To balance precision and reach, Amazon Ads employs a tiered thresholding approach. Different thresholds are applied at various levels of the audience hierarchy, allowing for nuanced adjustments that match the specific characteristics of behavioral audiences.
  • Addressing Training Bias: To overcome the covariate shift (discrepancies between training data and real-world data), Amazon Ads uses domain adversarial learning. This technique trains models to minimize prediction error while maximizing the discrepancy between source and target domains, ensuring robust audience predictions across different types of traffic.

Performance Metrics and Real-World Impact

Amazon Ads continuously monitors the performance of its modeled audiences through various KPIs, such as cost per action (CPA) and return on ad investment (ROAS). Their approach has shown significant improvements, including:

  • 20-30% additional delivery into cookieless environments
  • 25% increase in impression delivery
  • 12% more efficient CPMs

These metrics demonstrate Amazon Ads’ ability to reach previously inaccessible audiences without compromising performance, maintaining relevance across devices and browsers like Safari.

Future Directions: Beyond Modeled Audiences

Amazon Ads is not stopping at modeled audiences. The company is also developing additional contextual methods, including:

  • Semantic Relevance: Targeting criteria connected to related topics, ideal for reaching audiences based on their content consumption patterns.
  • Performance Relevance: Linking contexts with specific actions or conversions to optimize conversion rates, understanding patterns like “customers who read about topic X tend to purchase product Y.”

These strategies aim to enhance campaign performance in a world without third-party cookies, satisfying both advertisers and consumers.


Amazon Ads is pioneering the future of digital advertising by leveraging first-party signals and advanced modeling techniques to deliver relevant ads without third-party cookies. Their innovative approach ensures advertisers can continue to connect with their audiences effectively while respecting user privacy and adhering to new regulatory standards. As the industry moves forward, Amazon Ads’ strategies offer a robust framework for maintaining ad relevance in an evolving digital landscape.


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