
2024 marked a significant year. AI became integral to our workflows, commerce and retail media networks soared, and Google did not deprecate cookies. Amidst these changes, ID bridging emerged as a hot topic, raising questions around identity reliability and transparency, which necessitated industry-wide standards. We believe the latest IAB OpenRTB specifications, produced in conjunction with supply and demand-side partners, set up the advertising industry for more transparent and effective practices.
So, what exactly is ID bridging?
As signals, like third-party cookies, fade, ID bridging emerged as a way for the supply-side to offer addressability to the demand-side. ID bridging is the supply-side practice of connecting the dots between available signals, that were generated in a way that is not the expected default behavior, to understand a user’s identity and communicate it to prospective buyers. It enables the supply-side to extend user identification beyond the scope of one browser or device.

Imagine you visit a popular sports website on your laptop using Chrome. Later, you use the same device to visit the same sports website, but this time, on Safari. By using identity resolution tools, a supply-side partner can infer that both visits are likely from the same user and communicate with them as such.
ID bridging is not inherently a bad thing. However, the practice has sparked debate, as buyers want full transparency into the use of a deterministic identifier versus an inferred one. This complicates measurement and frequency capping for the demand-side. Before OpenRTB 2.6, ID bridging led to misattribution as the demand-side could not attribute ad exposures, which had been served to a bridged ID, to a conversion, which had an ID different from the ad exposure.
OpenRTB 2.6 sets us up for a more transparent future
In 2010, the IAB, along with supply and demand-side partners, formed a consortium known as the Real-Time Bidding Project for companies interested in an open protocol for the automated trading of digital media. The OpenRTB specifications they produced became that protocol, adapting with the evolution of the industry.
The latest evolution, OpenRTB 2.6, sets out standards that strive to ensure transparency in real-time bidding, mandating how the supply-side should use certain fields to more transparently provide data when inferring users’ identities.
What’s new in OpenRTB 2.6?
Here are the technical specifications for the industry to be more transparent when inferring users’ identities:
- Primary ID field: This existing field now can only contain the “buyeruid,” an identifier mutually recognized and agreed upon by both buyer and seller for a given environment. For web environments, the default is a cookie ID, while for app activity, it is a mobile advertising ID (MAID), passed directly from an application downloaded on a device. This approach ensures demand-side partners understand the ID’s source.
- Enhanced identifier (EID) field: The EID field, designated for alternative IDs, now accommodates all other IDs. The EID field now has additional parameters that provide buyers transparency into how the ID was created and sourced, which you can see in the visual below:

Using the above framework, a publisher who wants to send a cross-environment identifier that likely belongs to the same user would declare the ID as “mm=5,” while listing the potential third-party identity resolution partner under the “matcher” field, which the visual below depicts. This additional metadata gives the demand-side the insights they need to evaluate the reliability of each ID.

“These updates to OpenRTB add essential clarity about where user and device IDs come from, helping buyers see exactly how an ID was created and who put it into the bidstream. It’s a big step toward greater transparency and trust in the ecosystem. We’re excited to see companies already adopting these updates and can’t wait to see the industry fully embrace them by 2025.”
Hillary Slattery, Sr. Director, Programmatic, Product Management, IAB Tech Lab
Experian will continue supporting transparency
As authenticated signals decrease due to cookie deprecation and other consumer privacy measures, we will continue to see a rise in inferred identifiers. Experian’s industry-leading Digital Graph has long supported both authenticated and inferred identifiers, providing the ecosystem with connections that are accurate, scalable, and addressable. Experian will continue to support the industry with its identity resolution products and is supportive of the IAB’s efforts to bring transparency to the industry around the usage of identity signals.
Supply and demand-side benefits of adopting the new parameters in OpenRTB 2.6
- Partner collaboration: Clarity between what can be in the Primary ID field versus the EID field provides clear standards and transparency between buyers and sellers.
- Identity resolution: The supply side has an industry-approved way to bring in inferred IDs while the demand side can evaluate these IDs, expanding addressability.
- Reducing risk: With accurate metadata available in the EID field, demand-side partners can evaluate who is doing the match and make informed decisions on whether they want to act on that ID.
Next steps for the supply and demand-sides to consider
For supply-side and demand-side partners looking to utilize OpenRTB 2.6 to its full potential, here are some recommended steps:
For the supply-side:
- Follow IAB Specs and provide feedback: Ensure you understand and are following transparent practices. Ask questions on how to correctly implement the specifications.
- Vet identity partners: Choose partners who deliver the most trusted and accurate identifiers in the market.
- Be proactive: Have conversations with your partners to discuss how you plan to follow the latest specs, which identity partners you work with, and explain how you plan to provide additional signals to help buyers make better decisions.
We are beginning to see SSPs adopt this new protocol, including Sonobi and Yieldmo.
“The OpenRTB 2.6 specifications are a critical step forward in ensuring transparency and trust in programmatic advertising. By aligning with these standards, we empower our partners with the tools needed to navigate a cookieless future and drive measurable results.”
Michael Connolly, CEO, Sonobi
These additions to the OpenRTB protocol further imbue bidding transactions with transparency which will foster greater trust between partners. Moreover, the data now available is not only actionable, but auditable should a problem arise. Buyers can choose, or not, to trust an identifier based on the inserter, the provider and the method used to derive the ID. While debates within the IAB Tech Lab were spirited at times, they ultimately drove a collaborative process that shaped a solution designed to work effectively across the ecosystem.”
Mark McEachran, SVP of Product Management, Yieldmo
For the demand side:
- Evaluation: Use the EID metadata to assess all the IDs in the EID field, looking closely at the identity vendors’ reliability. Select partners who meet high standards of data clarity and accuracy.
- Collaboration: Establish open communication with supply-side partners and tech partners to ensure they follow the best practices in line with OpenRTB 2.6 guidelines and that there’s a shared understanding of the mutually agreed upon identifiers.
- Provide feedback: As OpenRTB 2.6 adoption grows, consistent feedback from demand-side partners will help the IAB refine these standards.
Moving forward with reliable data and data transparency
As the AdTech industry moves toward a cookieless reality, OpenRTB 2.6 signifies a substantial step toward a sustainable, transparent programmatic ecosystem. With proactive adoption by supply- and demand-side partners, the future of programmatic advertising will be driven by trust and transparency.
Experian, our partners, and our clients know the benefits of our Digital Graph and its support of both authenticated and inferred signals. We believe that if the supply-side abides by the OpenRTB 2.6 specifications and the demand-side uses and analyzes this data, the programmatic exchange will operate more fairly and deliver more reach.
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Tapad's integration with Knorex's XPO™ platform will complement cross-channel optimization capabilities for brands and agencies in the U.S. and APAC markets NEW YORK and SINGAPORE, Dec. 10, 2019 /PRNewswire/ — Tapad, part of Experian and a global leader in digital identity resolution, has partnered with Knorex, a leading provider of digital performance marketing. Knorex's self-service online advertising platform, Knorex XPO™, enables marketers to advertise globally in real-time across different media channels, formats, platforms and devices. Tapad's global, privacy-safe digital cross-device solution, The Tapad Graph, will compliment Knorex XPO™'s own device data set for enhanced marketing capabilities. For Knorex, the integration enables their brand direct and agency customers to gain a more accurate understanding of consumers across devices to reduce campaign inefficiencies and duplication, and to effectively manage frequency capping and attribution. Abhishek Kumar, VP of Engineering at Knorex commented, "Today's digital consumer is raising the bar for marketers. With increasing marketing complexities and consumer device usage, this integration enables marketers to understand the consumer decision journey with heightened ease. Our combined offering will empower agencies in the APAC and US markets, providing an improved marketing solution that will help to streamline their efforts." Abhay Doshi, Head of APAC at Tapad added: "The Tapad Graph, when integrated with the Knorex XPO platform, should not only help U.S. and APAC marketers optimize campaign performance through cross device marketing – but also increase the opportunity for brands to reach out to their target customers within a desired time." To learn more about Tapad and our digital identity resolution capabilities, visit https://www.experian.com/marketing/consumer-sync About TapadTapad, Inc. is a global leader in digital identity resolution. The Tapad Graph and its related solutions provide a transparent, privacy-safe approach connecting brands to consumers through their devices globally. Tapad is recognized across the industry for its product innovation, workplace culture, and talent, and has earned numerous awards including One World Identity's 2019 Top 100 Influencers in Identity Award. Headquartered in New York, Tapad also has offices in Chicago, London, Oslo, Singapore, and Tokyo. About KnorexKnorex provides programmatic advertising products and technologies to advertising buyers worldwide. With its cloud-based online advertising platform, Knorex XPO™ enables ad buyers to self-serve and advertise real-time across the globe regardless of the media channels (social, search, OTT/CTV, video, web/mobile etc.), ad formats (display, native, search, social, video etc) and devices (desktop, laptop, smartphones and tablets) to deliver personalized marketing messages to the target audience in an automated way, powered by machine learning/AI. Underpinned by a multi-layered data-driven approach, XPO simplifies the execution and optimization of marketing campaigns, while delivering measurable and attributable performance. Contact us today!

Tapad, now part of Experian, technology now powers Lifesight's real world intelligence platform with cross-device and reach expansion in the Asia Pacific Region SINGAPORE, Nov. 20, 2019 /PRNewswire/ — Tapad, part of Experian and a global leader in digital identity resolution, today announced a new partnership with Lifesight, a leading provider of real world intelligence for advertisers in the Asia Pacific region (APAC). With the combined offering of The Tapad Graph, Tapad's global, privacy-safe digital cross-device solution, and Lifesight's real world intelligence platform, brands and agencies across APAC can benefit from better consumer targeting, expanded reach for targeted audiences and web-to-mobile footfall attribution. Through this multi-layered offering, Lifesight's brand and agency partners can access an omnichannel view of consumers' paths to purchase, thereby enabling them to increase the reach, measurability and ROI of their advertising campaigns. Rohit Maheswaran, Co-founder of Lifesight commented, "The consumer journey is getting increasingly more complex with ever changing digital and physical world behaviours, making it difficult for marketers to make strategic marketing spend decisions. That's why it's our mission at Lifesight to empower the brands and agencies within the APAC market to achieve better targeting and measurement capabilities, and our partnership with Tapad will help further this cause." Abhay Doshi, Head of APAC at Tapad added, "The Tapad Graph, which enables a unified view of consumers across their multiple digital devices, has a reach of 1 billion devices across the APAC market today. Paired with Lifesight's consumer insights of more than 500 million unique devices, this valuable partnership will offer the market extended consumer reach and prove beneficial to brands and advertisers across APAC who have historically struggled with resolving attribution." To learn more about Tapad and our digital identity resolution capabilities, visit www.experian.com/marketing/consumer-sync About Tapad Tapad, Inc. is a global leader in digital identity resolution. The Tapad Graph, and its related solutions, provide a transparent, privacy-safe approach connecting brands to consumers through their devices globally. Our one-of-a-kind Graph Select offering enables marketers the flexibility and freedom of choice to correlate devices to varied objectives, driving campaign effectiveness and business results. Tapad is recognized across the industry for its product innovation, workplace culture and talent, and has earned numerous awards including One World Identity's 2019 Top 100 Influencers in Identity Award. Headquartered in New York, Tapad also has offices in Chicago, London, Oslo, Singapore and Tokyo. About Lifesight: Lifesight is Asia's leading real world intelligence company that helps marketers understand, target, and measure consumers based on their real world behaviour. Lifesight's robust platform and data solutions power business decisioning, audience activation, footfall measurement, and in-depth location analytics for leading brands and enterprises. The company is headquartered in Singapore with a rapidly expanding footprint in the Asia Pacific region operating in India, Malaysia, Indonesia, UAE, Saudi Arabia, Thailand, Philippines, Vietnam, Japan, Australia and New Zealand. To learn more, visit https://www.lifesight.io/ Contact us today!