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IAB Tech Lab clarifies complementary roles of Trusted Server and Prebid

Publisher-controlled middleware works alongside auction engine to deliver comprehensive ad solutions.

Luis Rijo

• 5 min read

The Interactive Advertising Bureau Technology Laboratory has published detailed clarifications addressing industry confusion about the relationship between Trusted Server and Prebid Server frameworks. According to IAB Tech Lab, the two technologies serve complementary rather than competing functions in modern digital advertising infrastructure.

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The announcement follows repeated questions from publishers and advertising technology companies since the Trusted Server initiative launched at the Signal Shift event in March 2024. Jason Evans, Trusted Server Technical Architect at IAB Tech Lab, explained that both software frameworks provide distinct value to publishers while working together to offer privacy-first monetization capabilities under enhanced publisher control.

Summary

Who: Interactive Advertising Bureau Technology Laboratory, with Jason Evans as Trusted Server Technical Architect

What: Publication of detailed analysis clarifying complementary roles of Trusted Server and Prebid Server frameworks in digital advertising infrastructure

When: Following Signal Shift event announcement in March 2024, with detailed documentation published addressing industry questions

Where: Global digital advertising ecosystem, focusing on publisher-controlled edge cloud middleware and server-side auction engines

Why: Address repeated industry confusion about relationship between technologies while demonstrating how both frameworks provide distinct value for privacy-first monetization capabilities under enhanced publisher control

Technical architecture differences

The Trusted Server operates as publisher-controlled edge cloud middleware functioning as an intelligent ad router. According to the documentation, it orchestrates between direct sold and programmatic sales while managing interactions with publisher ad servers and content. Its primary function enables capturing and packaging client-side signals normally collected by third parties through JavaScript code stored in browser local storage.

Key technical capabilities include signal collection and identity packaging, where the system collects on-page signals such as context, user behavior, and consent signals. The framework packages these elements to enable publisher third parties to provision services within server-side architecture independent of current or future browser restrictions.

The system maintains publisher monetization operations under the publisher's first-party domain, rewriting third-party ad tech calls to first-party calls. According to the technical specifications, this maintains advertising utility while managing ad-related data securely at the edge for enhanced performance.

Prebid Server functions as a server-side auction engine built and maintained by the Prebid community. Its role centers on running header bidding auctions, collecting bids from demand sources, and returning winning ad creatives. The system runs auctions by collecting bid requests from demand partners, scoring bids, and selecting winners while interfacing with supply-side platforms, demand-side platforms, and other demand sources.

Operational workflow integration

The request process demonstrates how both systems work together effectively. According to the technical documentation, Trusted Server first collects relevant signals when users visit pages, including contextual data, consent strings, synthetic identifiers, and other relevant signals. The system then handles identity and privacy by packaging data in privacy-safe manner under publisher control before sending to Prebid Server for auction execution using packaged identity and context data.

The response process shows Trusted Server ingesting auction results from Prebid Server. Once an ad is selected, Trusted Server stitches the creative into the Document Object Model, ensuring compliance and user experience standards remain maintained.

According to the detailed capability comparison, Trusted Server handles auction results interpretation responsibility while Prebid Server manages auction execution responsibility. The framework provides ad creative stitching including HTML and JavaScript rewrites, publisher DevOps control with reduced AdOps dependency, and request level edge storage for stored requests and cache.

Publisher control and data management

The system enables modular logic control rather than static execution of pre-configured adapters. According to technical specifications, it works with or without Prebid.js and supports modular third-party integrations including identity and brand safety components. Prebid Server provides bidder adapter direct integrations and OpenRTB bidstream control and communication.

Client-side signal packaging and manipulation capabilities distinguish Trusted Server operations. The system runs under publisher domains using first-party only calls while providing ability to rewrite and modify content and header responses. According to the documentation, it enables ad request routing based on rule sets including direct sold and real-time bidding configurations.

Server-side identity management includes SSID and consent management platform injection and syncing into the bidstream. The framework provides ability to set server-side HTTP cookies and global synthetic identifiers while supporting fraud detection and invalid traffic filtering.

Privacy and performance implications

The architecture addresses privacy concerns through orchestration of complete page logic with full context and user session visibility. According to IAB Tech Lab specifications, the system provides scalable mechanisms for consent management platforms, identity providers, measurement vendors, fraud detection, and other ad tech components to operate safely under publisher governance.

Performance optimization occurs through flexible integration that works without tags and doesn't require client-side scripting. This enables tagless or server-side implementations while preserving user experience and site performance through DOM integration that stitches final ad responses into page structure.

The framework specifically does not conduct auctions, according to technical documentation. Instead, it receives auction results from Prebid Server or other supply-side platforms and reconciles them with publisher ad servers against direct-sold prioritization.

Industry adoption and implementation

The modular approach allows publishers to implement robust, privacy-compliant advertising management in the post-cookie era. According to the technical specifications, Trusted Server functions as the publisher-controlled signal and rendering layer while Prebid Server remains the core auction engine.

Implementation considerations include edge cloud computing requirements, content management system integration, and coordination with existing ad tech infrastructure. The system supports both traditional and emerging advertising formats while maintaining compatibility with current publisher workflows.

Technical requirements encompass CDN edge compute capabilities, asynchronous operations from edge locations, and integration with ad-tech partner cloud or data center infrastructure. According to documentation, the system supports various cloud platforms including Amazon Web Services, Google Cloud Platform, and Microsoft Azure.

Market context and timing

The clarification addresses growing industry emphasis on privacy-first advertising solutions. PPC Land has documented numerous developments in this space, including cookieless advertising showing 40% lower value but early signs of progress, and IAB Tech Lab's release of frameworks for privacy-first digital advertising without IDs.

The announcement follows related IAB Tech Lab initiatives including the PAIR protocol for first-party data matching and ADMaP privacy-first attribution protocol. These developments reflect broader industry movement toward privacy-enhancing technologies in digital advertising.

Recent developments also include Yahoo's expansion of identity solutions to Connected TV and Google's introduction of new privacy tools in Display & Video 360, demonstrating continued innovation in privacy-preserving advertising technologies.

Technical implementation details

The comprehensive technical architecture includes multiple components working synchronously and asynchronously. Edge cloud content management systems handle initial requests through HTTPS protocols while CDN edge compute systems like Fastly manage processing. CDN edge workers including Akamai coordinate with cloud platforms for distributed processing.

Tagless asynchronous operations enable efficient data flow between components. According to technical diagrams, the system processes multiple simultaneous requests including async requests to HTML, first-party, and origin resources. The edge code response and bid routing system, functioning as the Trusted Server core, manages complex request orchestration.

Ad-tech partner integration occurs through cloud or data center connections supporting supply-side platforms and prebid servers. The architecture accommodates server-side identity endpoints while maintaining logging and measurement endpoint functionality throughout the process.

According to Evans, organizations interested in learning more about Trusted Server or participating in development can visit the Trusted Server page or contact IAB Tech Lab directly. The organization continues seeking new perspectives and contributions to help shape digital advertising's future.

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