In 2022, Google began changing the availability of the information available in User-Agent strings across their Chromium browsers. The change is to use the set of HTTP request header fields called Client Hints. Through this process, a server can request, and if approved by the client, receive information that would have been previously freely available in the User-Agent string. This change is likely to have an impact on publishers across the open web that may use User-Agent information today.
To explain what this change means, how it will impact the AdTech industry, and what you can do to prepare, we spoke with Nate West, our Director of Product.
What is the difference between User-Agents and Client Hints?
A User-Agent (UA) is a string, or line of text, that identifies information about a web server’s browser and operating system. For example, it can indicate if a device is on Safari on a Mac or Chrome on Windows.
Here is an example UA string from a Mac laptop running Chrome:
To limit the passive fingerprinting of users, Google is reducing components of the UA strings in their Chromium browsers and introducing Client Hints. When there is a trusted relationship between first-party domain owners and third-party servers, Client Hints can be used to share the same data.
This transition began in early 2022 with bigger expected changes beginning in February 2023. You can see in the above example, Chrome/109.0.0.0, where browser version information is already no longer available from the UA string on this desktop Chrome browser.
How can you use User-Agent device attributes today?
UA string information can be used for a variety of reasons. It is a component in web servers that has been available for decades. In the AdTech space, it can be used in various ad targeting use cases. It can be used by publishers to better understand their audience. The shift to limit access and information shared is to prevent nefarious usage of the data.
What are the benefits of Client Hints?
By using Client Hints, a domain owner, or publisher, can manage access to data activity that occurs on their web properties. Having that control may be advantageous. The format of the information shared is also cleaner than parsing a string from User-Agents. Although, given that Client Hints are not the norm across all browsers, a long-term solution may be needed to manage UA strings and Client Hints.
An advantage of capturing and sharing Client Hint information is to be prepared and understand if there is any impact to your systems and processes. This will help with the currently planned transition by Google, but also should the full UA string become further restricted.
Who will be impacted by this change?
Publishers across the open web should lean in to understand this change and any potential impact to them. The programmatic ecosystem supporting real-time bidding (RTB) needs to continue pushing for adoption of OpenRTB 2.6, which supports the passing of client hint information in place of data from UA strings.
What is Google’s timeline for implementing Client Hints?
Do businesses have to implement Client Hints? What happens if they don’t?
Not capturing and sharing with trusted partners can impact capabilities in place today. Given Chromium browsers account for a sizable portion of web traffic, the impact will vary for each publisher and tech company in the ecosystem. I would assess how UA strings are in use today, where you may have security concerns or not, and look to get more information on how to maintain data sharing with trusted partners.
We can help you adopt Client Hints
Reach out to our Customer Success team at tapadcustomersuccess@experian.com to explore the best options to handle the User-Agent changes and implement Client Hints. As leaders in the AdTech space, we’re here to help you successfully make this transition. Together we can review the options available to put you and your team on the best path forward.
About our expert
Nate West, Director of Product
Nate West joined Experian in 2022 as the Director of Product for our identity graph. Nate focuses on making sure our partners maintain and grow identity resolution solutions today in an ever-changing future state. He has over a decade of experience working for media organizations and AdTech platforms.
Latest posts
Privacy-forward pharma media supports more informed healthcare journeys Effective pharma marketing depends on reaching patients, caregivers, and healthcare professionals (HCPs) with useful information in appropriate, privacy-forward ways. The goal is to make relevant education easier to find, support more informed conversations, and help brands understand how media contributes across the health journey. In this Ask the Expert session, Natalie Mancuso, SVP, Data Partnerships at DeepIntent, joins Sheila Wirick, who leads the health team at Experian, to discuss how to craft patient and HCP campaigns, privacy-safe activation workflows, connected TV (CTV), and measurement approaches built for pharma. Why should your media plan start with understanding the patient and provider The patient-and-provider journey should inform your media plan, as treatment decisions in pharma are increasingly informed, personal, and patient-driven. With more health information available than ever, patients are playing a more active role in understanding their options and participating in treatment conversations. As other industries become more customer-centric, pharma media planning needs to become more patient-centric. “We’ve got patients who are more informed, more involved in their treatment decisions than ever. The accessibility of data and information and the ways we can consume it with just AI alone is so vast that if we’re not arming people with the right information in real time, we’re missing the boat.”Natalie Mancuso, SVP, Data Partnerships This means media should be aligned to where a patient or provider is in the decision journey and what they need at that moment. Early on, media may play an educational role by building awareness of a condition, symptom, or treatment category. Later, it may help support more specific questions, treatment consideration, access, affordability, or adherence. The patient-provider conversation remains the key boundary. That exchange should stay private and clinically led. Media can play a valuable role before and after those moments by offering information that helps patients and providers feel more informed. How can brands connect patient and HCP messaging responsibly? It’s critical for agencies and brands to deliver relevant messaging to inform each stakeholder’s needs throughout the treatment journey, especially ahead of key clinical milestones. To execute this, brands must exercise privacy-forward activation, keeping patient and HCP identity, activation, and measurement paths separate, while using a common workflow layer to support the same brand goal. Experian helps pharma marketers do this by acting as an independent, privacy-forward identity, data, and workflow layer. We bring together high-fidelity matching, governed onboarding, and non-clinical consumer context, so patient and HCP engagement can be activated more accurately across channels and connected to reporting. The distinction is not only where each audience is reached. HCPs may be engaged in both professional and personal environments, but their needs are different from patients’. For example, an HCP may receive messaging about co-pay savings for eligible patients, while a patient may receive information about patient support programs. These are different messages for different audiences, but they ladder up to the same goal: informing both parties in a privacy-forward, relevant way. Hear from Natalie Mancuso in our 2026 State of advertising report In our 2026 State of advertising report, Natalie shares why identity serves as the connective infrastructure that links planning, activation, and measurement across connected TV (CTV), programmatic, commerce media, and walled garden environments. Download the report Watch Natalie’s Q&A What does privacy-forward activation look like in pharma? Pharma brands often start with fragmented patient and HCP signals. Privacy-forward activation turns those inputs into usable audiences by first confirming that the data can be used, then translating identity in controlled environments that protect personally identifiable information through tokenization or other methodologies. For DTC, that means building and matching audiences without relying on inferred health conditions from browsing behavior. For HCPs, it means connecting professional identity to verified sources in a way that supports activation and measurement. In a category shaped by HIPAA, state privacy laws, internal review, and consumer sensitivity, building privacy in from sourcing through activation is what makes responsible health media possible. How can CTV play a more useful role in pharma? CTV can play a more useful role in healthcare when it’s connected to a larger, privacy-forward plan and not treated as just an awareness channel. DeepIntent connects CTV and digital exposure data using identity signals, such as National Provider Identifiers (NPIs), hashed email addresses, IP addresses, device IDs, and household signals, where permitted and reviewed. That identity layer helps support sequencing and suppression across streaming, endemic, mobile, and digital settings. In practice, CTV can introduce targeted education or broad brand awareness, and later touchpoints can provide sequential information in the right channels. Instead of repeating the same message, brands can make pivots based on engagement and context. “For us, it starts with identity and not panels. When we’re resolving CTV and digital exposures to the same person, we’re leveraging signals so that every touchpoint across streaming, endemic, and mobile is recognized as the same individual, not model lookalikes.”Natalie Mancuso, SVP, Data Partnerships For pharma, campaign performance should not be measured by reach alone. A stronger approach looks at whether sequenced engagement contributes to meaningful downstream signals, including: Prescription activity Provider engagement Referral patterns Patient compliance Adherence signals, where measurement is permitted Why should messaging and reporting change in pharma? Pharma campaigns are journeys with changing information needs. Reporting should guide the campaign optimization. “If I’m launching into a market with a new class of drug, I’m asking what education needs to be put into the market – from both an HCP and a consumer standpoint – to build awareness?”Natalie Mancuso, SVP, Data Partnerships Clicks and website visits still have a place, but they can’t tell the full pharma story. DeepIntent processes data in real time, giving brands an up-to-date read on how media connects to campaign engagement. Campaign signals can help teams optimize audience logic, creative, channel mix, or sequencing during a live campaign. Heading Test for Media & Text Block Content Test for Media &Text Block Learn more Heading Test for Media & Text Block Content Test for Media &Text Block Learn more Heading Test for Media & Text Block Content Test for Media &Text Block Learn more Explore how privacy-safe pharma activation can make an impact Experian brings marketing data and identity expertise for health marketing and DeepIntent adds pharma-specific activation experience. Together, we help brands connect patient and HCP strategies responsibly, with privacy built in from the start. Watch the full video with our experts to hear Sheila Wirick and Natalie Mancuso discuss patient and HCP messaging, CTV, privacy-safe activation, and outcome measurement for pharma brands. About our experts Natalie Mancuso SVP, Data Partnerships, DeepIntent Natalie Mancuso is SVP, Data Partnerships at DeepIntent and a leader in health-focused AdTech and DSP strategy. With over 20 years of experience growing billion-dollar healthcare brands, she turns complex data into scalable, performance-driven solutions that keep marketers ahead of industry change. Sheila Wirick Director of Health Sales, Experian Sheila Wirick is the Director of Health Sales at Experian with more than 20 years of experience in data and analytics. As Director of Health Sales at Experian Marketing Services, she collaborates with healthcare, pharmaceutical, and nonprofit organizations to apply data and insights that enhance customer retention, brand awareness, and acquisition. She is committed to helping organizations use data to deliver measurable results and meaningful impact. FAQs What makes a pharma audience activation-ready? A pharma audience is activation-ready when patient or HCP inputs can be translated into usable audiences with the right accuracy, controls, interoperability, and destination readiness. For patient engagement, that may include privacy-safe cohort construction, caregiver logic, non-clinical enrichment and appropriate exclusion rules. For HCP engagement, it may include governed identity inputs such as NPI, specialty, practice location, professional address and other verified attributes where appropriate. How can pharma brands sequence messages across channels responsibly? Pharma brands can sequence messages responsibly by giving each channel a clear role and using audience logic to maintain continuity. CTV and out-of-home can support awareness, social can reinforce the message, search can capture active research and point-of-care or rep-triggered channels can support decision moments. The workflow should preserve separation between patient and HCP identity strategies. What should pharma marketers measure beyond clicks and site visits? Pharma marketers should measure whether media connects to outcomes such as audience quality, prescription activity, qualified HCP engagement, verified delivery, referral patterns, therapy starts or adherence signals where permitted. These outcomes often depend on partner-enabled workflows, clean rooms, and aggregated outputs rather than direct end-to-end tracking. How does Experian help pharma brands connect identity, activation and measurement? Experian acts as an independent privacy-first identity, data, and workflow layer for pharma marketers. We help brands bring together identity, high-fidelity matching, governed onboarding, non-clinical consumer context, and partner interoperability so patient and HCP engagement can be activated more accurately across channels and connected more cleanly to partner-enabled measurement. Latest posts
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Use case #1: Identifying customer spending potential to boost growth for a retail chain Objective Solution Results The solution By syncing its cookies with the Digital Graph, the DSP gained access to related identifiers, including: This expanded identity universe gave the DSP a unified view of individuals and households, making it possible to connect impressions to conversions across devices and channels. With each weekly refresh, attribution models stayed accurate and up to date, turning fragmented signals into proof of performance. Results Within weeks, the DSP saw measurable improvements