Prebid’s User ID Module Guide for Publishers
The Prebid User ID module enhances ad targeting and increases the value of header bidding. How? It unifies user identifiers into comprehensive profiles, which further streamlines the identity resolution process.
As the industry moves away from third-party cookies, the Prebid User ID module provides a privacy-compliant solution that can keep your advertising methods future-proof.
In this article, we’ll break down the Prebid User ID module–how it operates, why it’s crucial, and how it can enhance your header bidding strategy. Ready to optimize your ad performance? Let’s dive in!
Understanding the Role of User Identification in Digital Advertising
Cookies, especially third-party cookies, have traditionally been used to store user data and track user behavior across different websites. However, their use has declined due to increased privacy regulations and the phase-out of third-party cookies by major browsers like Chrome and Safari.
In the past, third-party cookies were the primary tool for user identification. However, with growing privacy concerns the industry is shifting towards more privacy-friendly methods.
User ID modules have emerged as a solution to this challenge.
Unlike cookies, these modules can manage multiple identity solutions, integrating them into a single framework that respects user privacy. These modules generate and store user IDs based on first-party data, ensuring that user tracking is done in a compliant manner while still enabling effective ad targeting.
The Importance of User Identification for Publishers
User identification allows publishers to offer more targeted and personalized ad placements, which are more attractive to advertisers. But we’ll delve into this topic more later.
Simply put, user identification helps publishers maximize their ad inventory’s value. Moreover, as the industry shifts away from third-party cookies, publishers who adopt advanced user identification systems are better positioned to maintain and grow their advertising revenue.
What are Prebid Modules?
Prebid modules are self-contained extensions within the Prebid framework, designed to add specific functionalities that optimize and enhance the bidding process. These modules can manage pricing rules, perform currency conversions, assess viewability, handle identity resolution, and more.
They allow publishers to tailor the core framework for the header bidding process so that it that improves efficiency and effectiveness and meets their specific needs.
A quick recap: Prebid is an open-source framework widely used in programmatic advertising, particularly in header bidding. It allows publishers to conduct auctions where multiple advertisers bid on ad space simultaneously, maximizing the value of their inventory.
Types of Prebid Modules
Prebid.js and Prebid Server both support modular frameworks, meaning you can add optional plugins or modules to the core Prebid setup. These add-ons can address specific needs and enable advanced features.
Here are examples of some modules Prebid recommends for publishers to use:
| Module | Main purpose |
| Consent Management – GPP | Ensures compliance with global privacy regulations by working with Consent Management Platforms (CMPs) to pass user consent information to bidders. Essential for regions following the Global Privacy Platform (GPP). |
| Consent Management – TCF | Facilitates compliance with European privacy laws (GDPR) by integrating with CMPs to manage and transmit user consent information to bidders. Designed specifically for use in Europe under the Transparency & Consent Framework (TCF). |
| GPP Control – USNat | Works alongside the consentManagementGpp module to ensure Prebid.js adheres to privacy regulations in the U.S., specifically targeting the USNat string for national-level compliance. |
| GPP Control – US States | Complements the consentManagementGpp module to manage compliance with state-level privacy regulations in the U.S., covering sections 8-12 of the Global Privacy Platform. |
| GPT Pre-Auction | Prepares the necessary ‘global placement id‘ for auctions when using GAM, which is increasingly required for running successful ad auctions. |
| TCF Control | Enhances GDPR compliance by enabling specific actions and controls in Prebid.js for processing data under European ePrivacy regulations. Particularly useful for publishers with European audiences. |
The Role of User Identification in Header Bidding
User identification is very important in header bidding because the value of an ad impression significantly increases when advertisers can identify the viewer, even in a pseudonymous manner.
If advertisers know more about the person viewing the ad–such as previous behaviors, preferences, or associated data–they can bid more confidently and offer higher bids, knowing the ad will likely reach a valuable audience.
Conversely, when little is known about the viewer, the bids tend to be lower due to the uncertainty of reaching the right audience.
How header bidding works: a brief recap
Header bidding is a technology that allows publishers to offer their ad inventory to multiple demand partners simultaneously, without the need for direct deals. This approach gives advertisers access to premium inventory and bid-level data, enabling them to make more informed bidding decisions.
- Publishers add the header bidding code to the header of their webpage.
- When a user visits the site, this code triggers ad requests to multiple demand partners simultaneously.
- These partners then submit their bids within a specified time frame (usually between 200—600ms to avoid slowing down the page).
- The bids are sent to the publisher’s ad server (e.g., Google Ad Manager), where the highest bid wins the auction, and the corresponding ad is displayed on the webpage.
Challenges with Traditional User Identification Methods
What is Cookie Syncing?
Cookie syncing is a process in which two ad platforms share and match the information they have collected about a user to identify them across different systems better. This process uses a «cookie ID» stored in the user’s browser, which helps target ads more accurately.
However, because cookies are domain-specific, data collected by one tracker cannot be read by another, limiting the amount of information that can be gathered.
The Role of Cookie Syncing in User Identification
Cookie syncing allows different advertising platforms to map and exchange user IDs, enabling them to share the data they’ve collected about users.
For example, when a user visits a website with ads, their browser sends a request to an ad platform, which then creates a unique user ID. This ID is stored in a third-party cookie. Other platforms can sync with this ID through a process involving pixel URLs, allowing them to match their own user IDs with those of other platforms.
This bidirectional sync helps improve audience targeting across multiple platforms.
Limitations of Cookie Syncing
There are 3 main limitations of cookie syncing:
- Data loss and match rates. Cookie syncing can result in low match rates and data loss because of the fragmented nature of cookies across different domains and platforms.
- Privacy concerns and regulatory challenges. With increasing privacy regulations, such as GDPR and CCPA, cookie syncing faces significant challenges. Users are more aware of how their data is used, and regulations restrict how much data can be collected and shared.
- The decline of third-party cookies. The decline of third-party cookies, driven by privacy concerns and changes in browser policies, is rendering cookie syncing less effective. As third-party cookies become obsolete, alternative methods for user identification are becoming necessary.
Introduction to Prebid’s User ID Module
Ad tech vendors like The Trade Desk and LiveRamp, along with organizations like the IAB Tech Lab and the Advertising ID Consortium, have developed universal IDs. Since there are many ID solutions being developed, publishers need to understand how to work with them. Let’s get into that.
What is the Prebid User ID module?
The Prebid User ID module is an essential part of the Prebid open-source header bidding suite. It was created to streamline the use of multiple ID solutions within the ad ecosystem.
This module stores a unique user ID in the first-party domain (the publisher’s domain) and makes it accessible to all bidding partners. This unique ID is passed from the publisher (seller) to the advertiser (buyer) during the bidding process, creating a more accurate and effective ad targeting.
The module is designed to work with various standardized ID vendors, allowing them to provide sub-modules that publishers can integrate easily. This flexibility enables publishers to manage user identification efficiently, even as the industry transitions away from third-party cookies.
How the Prebid User ID module Enhances Header Bidding?
The Prebid User ID module represents a significant advancement in standardizing user identification for targeted advertising. Unlike third-party cookies, which rely on probabilistic methods to identify users, the Prebid User ID module leverages deterministic matching through first-party data.
This means that user IDs are more accurate and reliable, leading to better-targeted ads.
As a result, the Prebid User ID module increases the match rate (the ability to recognize users across platforms), improves bid rates, and ultimately drives higher CPMs for publishers.
- Simply put, this module enhances the overall efficiency and effectiveness of header bidding by ensuring that ads are displayed to the most relevant users.
Components and Functioning of the Prebid User ID module
Core Components of the User ID Module
The Prebid User ID module has a 3 key components that work together to handle user identification during the bidding process:
- User ID storage: stores the unique user ID within the publisher’s first-party domain. This ID is crucial for identifying users across different platforms without relying on third-party cookies.
- ID generators: these are tools provided by various ID solutions that generate unique user IDs based on first-party data. The module allows these generators to plug into the system easily.
- ID sharing: once the user ID is generated and stored, it’s shared with demand partners (advertisers) during the bidding process, helping them recognize and target users more effectively.
This module is used to integrate SharedID and other identity services into Prebid.js. Identity solution providers build submodules that are compatible with the user ID module. These submodules allow the services to get, set, and expose user identifiers to bidders.
Source: Prebid
Note: SharedID is an open-source identity solution from Prebid, which stores a unique user ID in the publisher’s domain. This identifier can be used by bidders in Prebid auctions for ad targeting, frequency capping or other purposes.
The SharedID system creates a user ID cookie within the publisher’s domain, meaning it’s stored as a first-party cookie. Because it’s a first-party cookie, it avoids the restrictions that browsers like Chrome and Firefox have placed on third-party cookies, which are cookies set by domains other than the one you’re visiting.
However, Safari imposes additional restrictions even on first-party cookies if they are set using certain methods, such as through document.cookie, which could limit the effectiveness of the SharedID system on that browser.
Technical Architecture: How the Module Integrates with Prebid.js?
Integration
The module is added to the Prebid.js setup as a plugin or extension. This means it can be included in the publisher’s header bidding configuration without significant changes to the existing setup.
Initialization
When a user visits a website, Prebid.js initializes the user ID module, which then triggers the ID generators to create or retrieve a unique user ID.
ID transmission
During the auction process, Prebid.js uses the module to pass the generated user ID to all bidding partners. This helps advertisers target their ads more accurately.
Bid adjustment
Advertisers use the user ID to adjust their bids based on the user’s profile, which leads to better-targeted ads and potentially higher revenues for the publisher.
How the Prebid User ID module Works?
The Prebid User ID module enables publishers to easily access and utilize various standardized ID solutions. These solutions are designed to improve user identification and ad targeting, ensuring a more efficient and effective bidding process.
With the module, publishers can manage first-party cookie identifiers directly within their header bidding wrapper (Prebid.js). This means that publishers can determine which user IDs are associated with which buyers without the need for complex and resource-intensive ID syncing across multiple demand sources.
Here’s a small breakdown on how exactly the Prebid User ID module works:
- Publishers first decide which user ID modules (from various ID providers) they want to include in their Prebid.js package. This selection allows them to choose the ID solutions that best fit their needs.
- Once the user ID modules are integrated, they generate the relevant user IDs. These IDs are then stored within first-party cookies on the publisher’s domain. This ensures that the user IDs are consistent and accessible across different sessions and platforms.
- The Prebid User ID module makes these generated IDs available within the bidstream—the data that is shared with potential buyers during the auction.
Ensuring Privacy Compliance with the Prebid User ID module
GDPR and CCPA Compliance
The Prebid User ID module is designed to help publishers comply with privacy regulations like GDPR and CCPA. These regulations require for user data to be handled with strict privacy controls, particularly concerning user consent for data collection and storage.
The user ID module works in tandem with the consent management module (CMM) to enforce privacy rules:
- The module checks the GDPR consent string to determine if the user has given consent for data storage and processing (specifically Purpose 1, which covers local storage like cookies).
If consent is not provided, the module ensures that no calls are made to external user ID vendors, and no data is stored in cookies or HTML5 local storage. This means the User ID module only activates when user consent criteria are met, ensuring compliance with privacy regulations.
Note: The CMM ensures that the User ID module operates according to the user’s consent choices, activating or deactivating ID-related processes based on whether consent has been granted.
Opt-Out Mechanisms for Users
To respect user privacy preferences, the Prebid framework allows publishers to implement opt-out mechanisms. If a user chooses to opt out, they won’t be tagged with first-party cookies containing IDs.
Publishers who wish to implement a first-party opt-out should design their workflow to set a special cookie _pbjs_id_optout or use HTML5 local storage. This ensures that user preferences are honored, and no IDs are stored if the user opts out.
For example, publishers can:
- Read from an in-page javascript variable and set
_pbjs_id_optoutto any value.
- Call an in-page function and use the results to create a
_pbjs_id_optoutcookie with any value.
ID Solutions Supported by Prebid’s User ID Module
As already mentioned before, Prebid’s User ID module supports a variety of ID solutions, giving publishers the flexibility to choose the ones that best fit their needs.
Functionality and Benefits of Different ID Solutions
Each ID solution supported by the Prebid User ID module specifically enhances user identification and ad targeting. The module generates, stores, and transmits standardized IDs within the bidstream, ensuring advertisers can recognize and target users more effectively.
By supporting multiple ID solutions, the module helps publishers improve their match rates, increase bid rates, and ultimately achieve higher CPMs.
One popular ID solution is the Unified ID. This ID solution is widely used because it creates a shared identifier that can be recognized across various platforms and vendors.
Another example is LiveRamp ID, which focuses on connecting user data across different platforms to create a more comprehensive user profile.
- Example case
Imagine a publisher using Prebid’s user ID module has chosen to integrate both the Unified ID and LiveRamp ID submodules. When a user visits the publisher’s website, the module generates a unique ID for that user and stores it in the first-party domain.
This ID is then shared with advertisers during the bidding process, allowing them to better target ads based on the user’s profile, leading to more relevant ads and higher bids.
Overview of Supported ID Solutions
We’ve gathered 9 universal ID sub-modules available within the Prebid User ID module, each provided by different standardized ID vendors. These sub-modules allow publishers to easily integrate various ID solutions into their header bidding setup.
Publishers have numerous options to choose from, for example:
| ID System Name | ID System Host | EID Source | Example Value | Explanation |
| Criteo ID for Exchanges | Criteo | criteo.com | “1111” | Criteo’s solution leverages its extensive data network to provide a robust user ID that enhances targeting across its demand sources. |
| ID5 Universal ID | ID5 | id5-sync.com | {uid: “1111”, ext: { linkType: 2, abTestingControlGroup: false } } | This solution provides a privacy-focused identifier that can be used in environments where third-party cookies are restricted or blocked. It’s designed to be a universal ID solution for the open web. |
| LiveIntent nonID | Live Intent | liveintent.com | “1111” | This ID solution focuses on identity resolution without the need for cookies, using deterministic data like email addresses (hashed) to create a user ID. |
| Lotame Panorama ID | Lotame | crwdcntrl.net | “e4b9…” | Lotame offers a data-rich ID solution that integrates its audience intelligence platform, providing enhanced data signals for better ad targeting. |
| Merkle ID | Merkle | merkleinc.com | “1111” | Merkle’s identity solution focuses on integrating customer data across platforms to provide a cohesive user ID that can be used across different channels. |
| Parrable ID | Parrable | parrable.com | {“eid”:”01.15946…”} | Known for its privacy-first approach, Parrable ID offers a solution that works without cookies, using device-level data to identify users across sessions. |
| PubProvided ID | n/a | publisher domain | “1111” | This allows publishers to set and pass a first-party user identifier directly into the bid stream. |
| Quantcast ID | n/a | quantcast.com | “1111” | This ID solution uses Quantcast’s vast data capabilities to create a reliable identifier that helps in targeting and measurement across the web. |
| Unified ID | Trade Desk | adserver.org | “1111” | This is one of the most widely adopted ID solutions. It creates a shared identifier recognized across multiple platforms, making it easier to target users consistently. |
Optimizing the Prebid User ID module for Maximum Revenue
How the User ID Module Improves Header Bidding Value?
The Prebid User ID module offers several significant benefits to publishers in digital advertising, particularly by enhancing the header bidding process.
Here are 4 main benefits the Prebid User ID module brings to the publisher’s table:
- Connects user data across platforms.
The module aggregates user data that is scattered across various platforms on the open web. By consolidating this data into a unified profile of individual users, it allows for more precise ad targeting.
This unified profile, sometimes referred to as «one-faced data,» helps advertisers understand who the user is across different sites and sessions, making their bids more relevant and effective.
- Improves header bidding value.
The Prebid User ID module enhances heder bidding by integrating multiple identity solutions. This improved accuracy in targeting further results in higher-quality bids.
The catch is simple–advertisers are willing to invest more in impressions that are well-targeted.
- Adapts to the post-cookie ecosystem.
With the ongoing phase-out of third-party cookies, the Prebid User ID module works as an alternative for user identification. It simplifies the integration of various ID solutions, enabling publishers to continue effective targeting without relying on cookies.
As already mentioned before, this is especially important as the industry shifts toward privacy-focused solutions.
- Increases inventory value and CPM.
By ensuring that detailed user data is available to advertisers, the module significantly enhances the value of a publisher’s inventory. Premium advertisers, who value precise targeting, are willing to pay more for ad placements that reach the right audience. This drives up the CPM.
Additionally, the higher the quality of the ad impressions, the higher the CPM. This module ensures that publisher’s header bidding setup includes high-performing ad units and accurate user targeting data.
Adapting to a Cookieless Future
We’ve said this once and we’ll emphasize it again–as third-party cookies are phased out, the industry is transitioning to a privacy-first approach.
In the Prebid cookieless future webinar it was stated that:
- Across all web browsers, 40% is already cookieless.
- On mobile in-app, 73% of Apple requests already withhold Device ID.
Note: Google is expected to implement similar restrictions for Android devices, further accelerating the transition to a cookieless environment.
Thus, marketers are using first-party data, exploring new tracking methods, and adopting new technologies. The key is that companies must focus on building customer trust by being transparent about data usage and offering personalized marketing that respects user privacy
The Impact of the phase-out of third-party cookies
The gradual phase-out of third-party cookies is compelling marketers to rethink their strategies. They are increasingly focusing on first-party data collection, where data is gathered directly from users with their consent.
Marketers are also exploring alternative data tracking methods that don’t rely on cookies, for example:
- Incrementality testing (to measure the true impact of marketing efforts)
- AI-powered predictive messaging (to anticipate user needs and behaviors)
- Contextual advertising (targeting ads based on the content being viewed rather than user history)
Preparing for a privacy-first advertising ecosystem
In a world that prioritizes privacy, marketers must invest in new technologies and approaches.
For example, Google Analytics 4 is being adopted for server-side tracking, which offers more control over data collection while adhering to privacy regulations. Alternative identifiers that rely on user consent, such as first-party cookies or login-based identifiers, are also becoming crucial.
Remember: transparent data practices are essential for building user trust in this new landscape!
Interoperability and seamless user experience
Interoperability is crucial in creating a seamless user experience in digital identity systems. It allows different systems and platforms to communicate effectively, ensuring that user identities can be verified and authenticated smoothly across various services and regions.
- For publishers using the Prebid framework, interoperability means that they can integrate multiple ID solutions (e.g., Unified ID) into their header bidding setup without facing compatibility issues.
This trend is supported by the development of standards like ISO/IEC 18013-5, initially designed for mobile driver licenses but now extended to cover a broader range of digital documents. Compliance with emerging privacy standards is important for publishers, as they ensure that their user identification processes are effective and secure.
Conclusion
The Prebid User ID module is a key asset for publishers aiming to enhance their header bidding and advertising efforts in a privacy-conscious world. By unifying user identifiers across multiple platforms, it simplifies the complex process of user identification, enabling more precise ad targeting and higher-quality ad impressions. This module not only boosts the effectiveness of header bidding by integrating various identity solutions but also ensures that publishers can maximize their revenue potential.
In an industry increasingly focused on data privacy and efficiency, the Prebid User ID module offers a comprehensive, future-proof solution for optimizing ad performance and maintaining a competitive edge.
FAQs
What is Prebid User ID module?
The Prebid User ID module is a tool that allows publishers to manage and unify user identifiers from multiple identity providers, improving ad targeting and header bidding performance.
How does the Prebid User ID module Work?
The module collects user identifiers from various sources, stores them in first-party cookies, and shares these unified IDs during header bidding to enhance ad targeting.
How Does the Prebid User ID module Ensure Privacy Compliance?
The module works with consent management systems to respect user privacy. It only activates and stores IDs when user consent is given, ensuring compliance with GDPR and CCPA.
What ID Solutions are Supported by the Prebid User ID module?
It supports multiple ID solutions, including Unified ID, ID5, LiveRamp, and others, allowing flexibility in choosing the best fit for your needs.
How Can the User ID Module Improve My Ad Revenue?
By enhancing ad targeting through better user identification, the module increases the value of ad impressions, leading to higher CPMs and greater revenue.
What are the Key Considerations for Integrating User IDs with GAM?
Ensure that the User ID module is correctly configured to sync with Google Ad Manager (GAM), focusing on passing the unified IDs to optimize ad targeting and reporting.
How Can Publishers Prepare for a Cookieless Future?
Publishers should integrate User ID modules to manage first-party data effectively, adopt privacy-compliant identity solutions, and explore alternative tracking methods like contextual advertising.
