Gathering Use Cases

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Hello Everyone,

I'd like to understand which real-world problems other developers want to solve with Client Hints, so I created this issue to collect use cases.

The use-cases I came up with are:

• Spam/Bot Detection – (the usefulness of the User-Agent header is declining due to easy spoofing, instead TLS fingerprinting & JavaScript fingerprinting is used as its more reliable)
• Download Pages – (basic platform information (OS, architecture, etc.) to prioritize the most relevant download options for users)
• Web Analytics

See the use cases identified by the specification authors in the UA Client Hints specification: https://wicg.github.io/ua-client-hints/#use-cases.

If you have additional use cases to suggest, please leave a comment. To keep the discussion focused, only comment if you're proposing a new use case. If you agree with a use case that has already been mentioned, please react with 👍 instead of posting a duplicate comment.

I personally think the same URL should always serve the same content, regardless of HTTP request headers.

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Responsive Images and Media
Use Client Hints to serve different images based on device pixel ratio, viewport width, data saver mode, etc.

(Although it's probably better to use the <picture> element with srcset, since it also lets you define different image URLs for each resolution or breakpoint.)

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Save-Data
Use Client Hints to serve different HTML based on the user’s Data Saver setting (without relaying on JavaScript). This helps deliver lighter content to users in regions where internet bandwidth and device performance are limited. Many users on low-powered devices also rely on browsers that disable JavaScript after page load, so adapting content server-side improves accessibility and performance. See World Wide Web, Not Wealthy Western Web (Part 1) for more info.

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Redirect to Mobile-Optimized Site
Use Client Hints to determine whether the device is mobile and optionally serve or redirect to a mobile-optimized version of the site.

See device type definitions in UAParser.js Documentation for ideas on additional device categories.

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No JavaScript Version
Although this is not supported in the current specification, there is a use case where content is adjusted based on whether the client supports JavaScript. If JavaScript is not available, a pre-rendered version of the application can be served. Otherwise, the full single-page application (SPA) code is delivered.