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OpenRTB and User-Agent Client Hints

The IAB recently published an updated version of the OpenRTB specification. The updated document, a revision to version 2.6 of the specification, now addresses the landscape change brought about by Google’s decision to progressively reduce the content of the user-agent string in Chrome in favour of User Agent Client Hints (UA-CH). 

This update provides welcome clarity for the OpenRTB ecosystem since Google's change would have threatened to weaken the ability of the OpenRTB protocol to support targeting by device type and other non-PII characteristics.

With the newest update, the OpenRTB specification now explicitly defines how to populate the ua attribute and the sua attribute in the case where a browser supports User-Agent Client Hints:
 

For backwards compatibility, exchanges are recommended to always populate ua with the User-Agent string, when available from the end user’s device, even if an alternative representation, such as the User-Agent Client-Hints, is available and is used to populate sua. No inferred or approximated user agents are expected in this field.

If a client supports User-Agent Client Hints, and sua field is present, bidders are recommended to rely on sua for detecting device type, browser type and version and other purposes that rely on the user agent information, and ignore ua field. This is because the ua may contain a frozen or reduced user agent string. 


This IAB update is welcome news for the industry and will help to provide continuity of operations for businesses. Currently, of the major browsers, only Google Chrome and Microsoft Edge have openly backed Google’s initiative, though this represents a large segment of web traffic (between March 2021 and 2022, Google Chrome and Microsoft Edge combined represented 69% of all browser traffic). Apple and Mozilla are not supporting the initiative. 

We would like to highlight the work of Rob Hazan at Index Exchange in making this update to the OpenRTB Device Object.


You can visit our HTTP Headers Parser to see how DeviceAtlas supports User-Agent Client Hints today. 


 

Related tags


client hints