Sec-CH-UA Client Hints

Category: Network / Connectivity
Type: New or changed feature
Status: Enabled by default (Chrome 89)
Intent stage: Shipped

Summary

The set of Sec-CH-UA-* client hints aims to deprecate and replace the User-Agent header in order to reduce the passive fingerprinting surface we expose via HTTP requests.

Motivation

Standards & signals

Specification: https://wicg.github.io/ua-client-hints
Firefox: Neutral
Safari: No signal
Web developers: Mixed signals — Some developers are receptive to the new API and its advantages over the User-Agent string, while others have filed issues on the repo to address their use cases, or to express concerns about the API. In addition, some User-Agent parsing services have been updated to include support for UA-CH.
Tracking bug: https://bugs.chromium.org/p/chromium/issues/detail?id=928669

Docs: https://github.com/WICG/ua-client-hints#explainer-reducing-user-agent-granularity https://github.com/WICG/client-hints-infrastructure#readme https://web.dev/user-agent-client-hints

Samples: https://goo.gle/ua-ch-demo

Explainers: https://github.com/WICG/ua-client-hints#explainer-reducing-user-agent-granularity

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