Client Hints Entropy Auditor
User-Agent Client Hints were designed to reduce fingerprinting — but requesting high-entropy values brings it right back. This auditor reveals every hint your browser exposes and estimates how many bits of identifying entropy they add up to.
Tool interface
Entropy audit
Revealed hints
| Hint | Value | Est. bits |
|---|
Bit values are estimates based on general web-population diversity, not a precise measurement of your specific user base. Empty or unavailable hints contribute 0 bits.
Introduction
The User-Agent Client Hints API replaces the monolithic UA string with granular, on-demand hints. The privacy win depends on requesting as little as possible. This tool helps you see exactly how much entropy a full request reveals.
How it works
- Reads default low-entropy hints from
navigator.userAgentData. - Calls
getHighEntropyValues()for all available high-entropy hints. - Assigns each hint an estimated bit contribution.
- Sums them into a total and classifies the fingerprinting risk.
Privacy
All reads are local via the Client Hints API. No data leaves the browser. No account, no API key.
Limitations
- Bit estimates are approximations, not precise measurements.
- Not implemented in Safari or Firefox.
- Actual entropy depends on the specific site's audience.
FAQ
What are high-entropy Client Hints?
Values like device model, CPU architecture, and full browser version that significantly narrow down which device a user is on. They must be explicitly requested.
Is my data uploaded?
No. Everything is read locally in your browser.