
Update: User-Agent Client Hints Progress 2023 Q1
For over a year now, we have been preparing for, deploying solutions, and reporting on the progress of user-agent client hints. Google continues to push forward with its plans to replace the user-agent string with user-agent client hints. This technology change has a big impact on device detection.
What Changes Do I Need to Make for User-Agent Client Hints
First of all, if you use ScientiaMobile’s various forms of WURFL device detection, you are in a good position. Since early 2022, WURFL API has incorporated user-agent client hints into its device detection.
However, users still need to “turn on” user-agent client hints on their servers. Configure your application and HTTP servers to request additional Client Hints headers. You can learn more about how to do this here.
If you have an open source UA Parser, you should seriously consider switching to a more accurate solution like WURFL immediately. These poorly maintained UA Parsers are inaccurate more than 22% of the time, and in February that accuracy will decline dramatically. Learn more here.

If you are already a WURFL user, make sure you
1) have installed the most updated API version and most recent device data XML snapshot file from my.scientiamobile.com
2) Opt in to request user-agent (UA) client hints by following these instructions
Since WURFL already uses UA client hints and can identify frozen user-agent strings, WURFL is ready for Google’s transition. WURFL device detection provides the highest level of accuracy and support in the industry.


A critical part of Google’s roll out involves freezing the user agent string. Let’s look at progress to date for both desktop and mobile.
Update: Frozen Desktop User Agent Strings as of 2023 Q1
Google has started to freeze more user agent strings with each subsequent version of their Chrome browser. In March 2022, they started with version 100 of Chrome for desktop browsers.
MOVR data started to observe these frozen user strings, showing 14% of observed user-agent strings were frozen in 2022 Q1. A year later in 2023 Q1, we have reached 73% of desktop user-agent strings are frozen.
Update: Frozen Mobile User Agent Strings as of 2023 Q1
Google has staggered the rollout of the freeze of mobile user-agent strings. As of today, April of 2023, Google has rolled our version M110 with user-agents partially frozen. In early April, Google stated it has enabled 10% of Android clients on M110 and above.
Almost no Mobile UA strings were frozen during 2023 Q1. Only 0.38% of observed mobile user-agent strings were frozen
According to Chromium.org, Phase 6 rollout is enabled for 50% of Android clients on version M110 and above as of April 25th, 2023. Based on this statement, next quarter (2023 Q2) is likely to see a significant increase in frozen Mobile UAs.
Google has forced a huge amount of change on the digital advertising industry recently. With their control over Google Chrome, the world’s most popular browser, and their pre-eminent control over Adwords and other forms of digital advertising, Google has the power to change some of the fundamental building blocks of the internet.
In previous blogs, we have outlined these changes and what you need to do to prepare and ensure device detection remains accurate.
What if My Home-Grown Detection System is Not Accurate?
If you are in advertising or use device detection in any way, you need to make adjustments to keep your device detection accurate. Hopefully, you already use WURFL device detection, because WURFL has already made changes to integrate User-Agent Client Hints, recognize frozen user-agent strings, and reconcile these two sources to ensure accuracy.
If you have a home-grown system that is suffering from poor accuracy, that is not a surprise. Most user-agent parsers (both home-grown and open source) are inaccurate 22% of the time. Read more about why that accuracy is getting worse. Keeping track of new devices is difficult enough for companies for whom it is not their core mission. JavaScript hacks that do simple UA sniffing are not going to work well going forward.
ScientiaMobile will perform a free User-Agent Client Hints Health Check for you. Our experienced customer success team can look at your current device detection processes and provide recommendations for best practices. Many customers have found this process very helpful for maintaining and improving their device detection processes.

Learn more about User-Agent Client Hints
Below is ScientiaMobile’s webinar about User-Agent Client Hints.
We go into detail about:
1:25 What is WURFL (Wireless Universal Resource FiLe)?
2:10 What is Google changing in User-Agent Strings and User-Agent Client Hints?
3:10 WURFL device detection automatically accepts UA Client Hints
3:30 UA Client Hints Timeline and Google
7:15 What to UA Client Hints Do?
10:00 Myths about UA Client Hints
16:20 What Should People do to Implement UA Client Hints?
22:00 How WURFL works with UA Client Hints: