Helping you navigate Google’s transition to Client Hints

January 31, 2023 by Experian Marketing Services

Client Hints are replacing User-Agents

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, if approved by the client, a server can request to 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:

User-Agent string example. Client Hints are replacing User-Agent strings across Chromium browsers.

To limit the passive fingerprinting of users, Google is reducing components of the UA strings in their Chromium browsers and introducing Client Hints. You can use Client Hints to share the same data when there is a trusted relationship between first-party domain owners and third-party servers.

This transition began in early 2022 with bigger expected changes beginning in February 2023. You can see in the above example, Chrome/, 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?

You can use UA string information for a variety of reasons. It is a component in web servers that has been available for decades. In the AdTech space, you can use it in various ad targeting use cases. Publishers can use it 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 for managing UA strings and Client Hints may be necessary.

An advantage of capturing and sharing Client Hint information is to be prepared and understand if there is any impact on 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 on them. The programmatic ecosystem supporting real-time bidding (RTB) needs to continue pushing for the 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?

Google's timeline for implementing Client Hints in Chromium browsers

Timeline source: Google

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, whether 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 headshot

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.