What Browser Fingerprints Are Exposed? A Guide from User-Agent to Client Hints

When performing website analysis, anti-scraping measures, or ad campaigns, User-Agent parsing is almost unavoidable. Many systems still rely on UA to determine device type, browser version, and even use it as a key factor for browser fingerprinting.

However, the problems are becoming increasingly obvious: redundant information, low cost of spoofing, and a high risk of privacy compliance issues.

Today, we’ll clarify the differences between HTTP Client Hints and User-Agent, their respective use cases, and their real impact on browser fingerprinting, helping you avoid common pitfalls.

1. User-Agent Parsing : How Much Information Does It Reveal?

A traditional User-Agent header usually looks like this:

Even though it’s just a string, it actually contains a lot of information:

• Operating system type and version

• Browser name and version

• CPU architecture

• Engine details

After parsing the User-Agent, the server can basically reconstruct a user’s device environment. This is useful for statistics and compatibility, but there are clear downsides:

1. High browser fingerprinting dimension

UA is often used as an important part of the fingerprint, combined with fonts, Canvas, and WebGL, making it easy to form a stable fingerprint.

2. Increasing privacy risks

UA information is "passively reported," and users cannot perceive or control it.

3. Low spoofing cost

Crawlers and automation tools can easily modify the UA and bypass many systems.

Because of these issues, Chrome has started to gradually deprecate the User-Agent.

2. What Are HTTP Client Hints?

HTTP Client Hints are a mechanism for "providing information on demand."

Simply put: the browser does not send all information at once; instead, the server requests what it needs, and the browser provides that.

Common Client Hints include:

• Sec-CH-UA: Browser brand

• Sec-CH-UA-Platform: Operating system

• Sec-CH-UA-Mobile: Whether it is a mobile device

• Sec-CH-UA-Full-Version (high-precision)

A key point is that high-precision information is only returned if the server explicitly requests it, fundamentally reducing unintentional information leakage.

3. How Client Hints Improve Privacy

• Principle of Minimal Exposure

If you don’t request it, it won’t be provided, preventing the "unintended disclosure of lots of information."

• Reduce stable fingerprint formation

Different sites request different hints, making cross-site tracking much harder.

• Better compliance with privacy regulations

More friendly to GDPR and data minimization principles.

For this reason, Client Hints are considered the next-generation solution for browser identity recognition.

4. Will User-Agent Be Completely Deprecated?

The answer: not in the short term, but its importance will decline. The reality is:

• Legacy systems and old code still rely on User-Agent parsing

• Many third-party SDKs have not fully adopted Client Hints

• Some anti-bot measures still rely on UA characteristics

A reasonable approach currently is: combine User-Agent + Client Hints, using UA for basic compatibility checks and Client Hints for more precise and compliant device identification.

5. Actual Impact on Browser Fingerprinting 

From a fingerprinting and risk control perspective, Client Hints bring significant changes:

• Reduced fingerprint stability

• Higher information access threshold

• Pure header-based fingerprints become increasingly unreliable

This also means that many risk control systems are moving towards multi-dimensional behavioral features + environment consistency checks, instead of relying solely on request headers.

Summary

In retrospect, HTTP Client Hints are not meant to "completely eliminate" User-Agent but rather to draw a line between privacy and functionality.

In the long term, the era of relying solely on User-Agent for device identification or risk control is over. Whether for anti-scraping, risk control, or SEO data analysis, it’s necessary to handle request header information more carefully and avoid over-reliance on a single dimension.

If you want a more intuitive understanding of which fingerprint features are exposed in the current environment, tools like ToDetect Fingerprint Lookup can be a useful reference, helping you quickly identify issues and verify your approach.