Updates to User-Agent Client Hints: 51Degrees Version 4.4


6/14/2022 5:00 PM

User Agent Client Hints Google Version 4 51Degrees News

Full User-Agent Client Hints support is now available

Launching in Version 4.4, 51Degrees real-time data service now fully supports User-Agent Client Hints and the reduction of the User-Agent in Chromium browsers.

You can now download the latest data files which contain full User-Agent Client Hints data.

Get support for User-Agent Client Hints

51Degrees User-Agent Client Hints support

User-Agent Client Hints (UA-CH) are a set of HTTP headers that relay information on the device (such as the browser or hardware) from the client to the server. UA-CH are only sent over HTTPS connections and are not sent over HTTP connections.

We’ve created a demonstration of User-Agent Client Hints which you can test for yourself (make sure you are accessing our resource over a HTTPS connection).

Version 4.3 of our service introduced User-Agent Client Hints support, which we have now refined in Version 4.4. This was a result of collecting live UA-CH data in response to Google changing the UA-CH specifciation.

Our User-Agent Client Hints documentation page details the technical aspects surrounding our User-Agent Client Hints support.

On 28 September 2022, we also hosted a webinar on User-Agent Client Hints; catch it on replay here or read an edited transcript here.

Should I be concerned about User-Agent Client Hints?

Starting in Chrome 101, released on 26 April 2022, Google began the reduction of the User-Agent within Chromium browsers. Information on the device and browser is now sent through User Agent Client Hints.

If you rely on UA string data, whether it’s for your website analytics or to ensure your app is compatible for any device, this change is crucial.

In October 2022, the release of Chrome 107 brought a reduced Desktop User Agent string. February 2023 and Chrome 110 brought the next phase of the User-Agent reduction with a reduced mobile User-Agent. Next year, Chromium browsers will cease to have any User-Agent data at all. And finally, the User-Agent reduction concluded in April 2023.

Web developers and site owners need to ensure they have migrated their web offerings to support User-Agent Client Hints. Otherwise, your websites may break.


What else is new in Version 4.4?

In addition to User-Agent Client Hints support, Version 4.4 of our on-premise product is backward compatible with our older Version 4 data files. However, the latest data files containing UA-CH data will only work with Version 4.4 of our product.

Finally, our latest data files contain newly updated detection graphs. Our new export process builds separate performance and predictive detection graphs for the different headers (e.g., User-Agent or UA-CH) as well as each of their components (e.g., hardware or browser). All of this results in a more accurate detection for you.

To summarize, in order to have full User-Agent Client Hints support and to future-proof your web offerings against Google’s changes, you must be using Version 4.4 of our service with the latest data files.

How to get started with Version 4.4

The following sections detail the steps you must take to get started with UA-CH support for both new and existing customers. For existing customers, we have segmented the instructions for Version 3 and 4 users, as well as cloud or on-premise implementations.

Jump to:

New customers

On-premise customers using Version 3

On-premise customers using Version 4

Cloud customers using Version 3

Cloud customers using Version 4

Skip to next section: Can Google change the industry?

New customers

First, take a look at our pricing plans to see which one suits you. We have both free and paid options, with hosting by you, on-premise, or our hosted service. There’s an option for everyone.

If you want to use our hosted service, you can use our Cloud Configurator to generate a Resource Key. This Resource Key should contain all the properties you wish to collect data for (some advanced properties may require the purchase of a License Key). For UA-CH support you will need the following properties:

  • SetHeaderHardwareAccept-CH

  • SetHeaderPlatformAccept-CH

  • SetHeaderBrowserAccept-CH

If you’d prefer to host our service on your own servers, you can do so with the purchase of a License Key. This Key allows you access to a data file containing all the properties with regular automatic updates Monday through Fridays. Or you can download our free data file, which is updated monthly but is very limited in the properties it contains.

Following your Resource Key generation (if you are using our cloud service) or License Key purchase, you can follow our quick start guide to help get you up and running with Device Detection or Geolocation. If you have any questions, do let us know.

On-premise customers using Version 3

We recommend any of our on-premise customers using Version 3 or earlier to upgrade to Version 4.

Without upgrading, your real-time data will become inaccurate as Chromium-based browsers begin the wide-spread freeze of the UA string. Considering Chromium’s dominance within the browser market, this would mean you miss out on a huge amount of data.

Additionally, Version 4 of our service is faster, has a smaller data file, and has an improved algorithm that allows better detection of new, different, and rare User-Agents.

To begin the upgrade process, please contact our sales team. They will help set you up with a new License Key so you can then follow the migration guide for your specific language. If you have any questions, please contact the team.

On-premise customers using Version 4

If you already use Version 4 of the 51Degrees service, but are on Version 4.1, 4.2, or 4.3, you will need to install the 4.4 packages and download the latest data file to have full UA-CH support. These packages can also be found on the 51Degrees GitHub.

Cloud customers using Version 3

If you are using an earlier Version of the 51Degrees cloud service and would like to upgrade to Version 4, please contact our sales team. They will help set you up with a new License Key, which you will need when you generate a Resource Key with your chosen properties via our Cloud Configurator.

To get started with User-Agent Client Hints support within the cloud service, you will need to add the following properties to your Resource Key generation:

  • SetHeaderHardwareAccept-CH

  • SetHeaderPlatformAccept-CH

  • SetHeaderBrowserAccept-CH

Please refer to our UA-CH documentation for more information on how to use these new properties.

Cloud customers using Version 4

UA-CH support is automatically available to our Version 4 cloud customers. All you need to do to start collecting UA-CH data is regenerate your Resource Key with our Cloud Configurator to contain the following Accept-CH Header properties:

  • SetHeaderHardwareAccept-CH

  • SetHeaderPlatformAccept-CH

  • SetHeaderBrowserAccept-CH

Please refer to our UA-CH documentation for examples on how to use these properties in the Pipeline.

Can Google change the industry?

Despite protest, Google are still going ahead with their plans to deprecate and freeze the User-Agent string, replacing them with User-Agent Client Hints.

It’s a shocking decision when you consider that Google:

  • Have yet to finalize the UA-CH specification, which at the time of writing (and updating in July 2023), still reads "Unofficial Draft".
  • Have not had their proposals approved according to the internet standardization process.
  • Are currently being monitored to ensure their Privacy Sandbox proposals protect privacy in a way that doesn't distort competition.

When you are the dominant player within the industry, is it fair to force others to adopt your proposals, despite glaringly obvious flaws?


Late in 2021, we raised an issue with the UK Competition and Markets Authority requesting they review their position and use their power to delay Google’s changes and include a reasonable transition period.

And in February 2022, the CMA accepted commitments from Google over their Privacy Sandbox proposal. This means that the UK CMA will be monitoring the changes proposed by Google to ensure that they benefit consumers. Google provided the CMA with its first quarterly report in May 2022.

This shows the power of challenging walled gardens. It may seem like a scary prospect, but to prevent Google ruling over the web, all market participants need to be prepared to raise concerns.

One way to do this is to join Movement for an Open Web (MOW), a group that has led the charge in ensuring big tech companies do the right thing for consumers.

The future of User-Agent Client Hints

There's still a lot of holes left in Google’s User-Agent Reduction proposal alongside User-Agent Client Hints, which is very concerning.

Unfortunately, we’re at mercy to the timelines proposed by Google on the User-Agent Reduction, and these are often subject to last minute changes. We do the best we can to move forward in such an uncertain world and can only follow the dates that are imposed on us by Google.

We encourage our customers to enable usage sharing and share User-Agent Client Hint data with us. This allows our machine learning to evolve alongside any new developments Google make to the HTTP header.

The best thing you can do is ensuring your website, app, or ad, has support for User-Agent Client Hints. Use Version 4.4 of the 51Degrees service alongside the latest data files to get full User-Agent Client Hints support.