Client Hints

Client Hints are a set of HTTP request header fields for proactive content negotiation allowing clients to indicate a list of device and user-agent specific preferences.

Every time you visit this page, the server responds with this HTTP headers:

Response Headers sent by the Server

Accept-CHviewport-width, dpr, device-memory, rtt, downlink, ect, ua, platform, arch, model, mobile
Accept-CH-Lifetime30

If you revisit browserleaks.com within 30 seconds, your browser should send HTTP Client Hints request headers: Viewport-Width, DPR, Device-Memory, RTT, Downlink, ECT, and User-Agent Client Hints request headers: Sec-CH-UA, Sec-CH-UA-*.

Client Hints received for the main document

Viewport-Widthnot received
DPRnot received
Device-Memorynot received
RTTnot received
Downlinknot received
ECTnot received
Sec-CH-UAnot received
Sec-CH-UA-Platformnot received
Sec-CH-UA-Archnot received
Sec-CH-UA-Modelnot received
Sec-CH-UA-Mobilenot received

Client Hints received for the iframe subrequest

HTTP Client Hints are currently only available in Chrome and some Chromium-based web browsers. User-Agent Client Hints are only under enable-experimental-web-platform-features Chrome flag.

If the User-Agent Client Hints feature is enabled, it will also expose a new JavaScript interface accessible through the navigator.getUserAgent() promise.

Client Hints Description

Description of currently available HTTP Client Hints:

User-Agent Client Hints:

Further Reading

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