Home>Client Hints

Client Hints are a set of HTTP Headers and a JavaScript API that allow web browsers to send detailed information about the client device and browser to web servers.They are designed to be a successor to User-Agent, and provide a standardized way for web servers to optimize content for the client without relying on unreliable User-Agent string - based detection or browser fingerprinting techniques.

HTTP User-Agent

Client Hints JavaScript API

API Support

False

Client Hints HTTP Headers

Client Hints are not yet fully standardized and are not supported by some browsers. They are sent by the client and may not be received due to caching or failure of the client to send the value.

sec-ch-ua

Not received

sec-ch-ua-platform

Not received

sec-ch-ua-mobile

Not received

sec-ch-ua-full-version

Not received

sec-ch-ua-full-version-list

Not received

sec-ch-ua-platform-version

Not received

sec-ch-ua-arch

Not received

sec-ch-ua-bitness

Not received

sec-ch-ua-wow64

Not received

sec-ch-ua-model

Not received

sec-ch-lang

Not received

sec-ch-save-data

Not received

sec-ch-width

Not received

sec-ch-viewport-width

Not received

sec-ch-viewport-height

Not received

sec-ch-dpr

Not received

sec-ch-device-memory

Not received

sec-ch-rtt

Not received

sec-ch-downlink

Not received

sec-ch-ect

Not received

sec-ch-prefers-color-scheme

Not received

sec-ch-prefers-reduced-motion

Not received

sec-ch-prefers-reduced-transparency

Not received

sec-ch-prefers-contrast

Not received

sec-ch-forced-colors

Not received

sec-ch-ua-form-factors

Not received

List of known Client Hints

```
Sec-CH-UA
```
Indicates the brand and version of the user agent
```
Sec-CH-UA-Full-Version
```
Indicates the full version of the user agent (deprecated, replaced by Sec-CH-UA-Full-Version-List
```
Sec-CH-UA-Full-Version-List
```
Represents the full version of each brand in its brand list.
```
Sec-CH-UA-Platform
```
Indicates the platform on which a given user agent is executing.
```
Sec-CH-UA-Platform-Version
```
Indicates the platform version that a given user agent is executing on.
```
Sec-CH-UA-Arch
```
Represents the architecture of the platform on which a given user agent is executing.
```
Sec-CH-UA-Bitness
```
Indicates the bitness of the platform architecture on which a given user agent is executing.
```
Sec-CH-UA-WoW64
```
Used to detect if the user agent binary is running in 32-bit mode on 64-bit Windows.
```
Sec-CH-UA-Model
```
Represents the device on which a given user agent is executing.
```
Sec-CH-UA-Mobile
```
Used to detect if the user agent prefers a "mobile" user experience.
```
Sec-CH-UA-Form-Factors
```
Indicates the form factor of the device, historically represented as the <deviceCompat> token in the User-Agent string.
```
Sec-CH-Lang
```
(or Lang) represents the user's language preference.
```
Sec-CH-Save-Data
```
(or Save-Data) represents the user agent's preference to reduce data usage.
```
Sec-CH-Width
```
Provides the layout width of the image to the server.
```
Sec-CH-Viewport-Width
```
(or Viewport-Width) is the width of the user's viewport in CSS pixels.
```
Sec-CH-Viewport-Height
```
Represents the current viewport height of the user agent.
```
Sec-CH-DPR
```
(or DPR) reports the ratio of physical pixels to CSS pixels of the user's screen.
```
Sec-CH-Device-Memory
```
(or Device-Memory) shows approximately how much memory the device currently has (in GiB). Because this information can be used to identify the user, the value of Device-Memory is intentionally rough. Valid values are 0.25, 0.5, 1, 2, 4, and 8.
```
Sec-CH-RTT
```
(or RTT) provides the approximate round-trip time in milliseconds at the application layer. RTT is different from the transport layer RTT in that it includes server processing time. The value of RTT is rounded to the nearest 25 milliseconds to prevent fingerprinting.
```
Sec-CH-Downlink
```
(or Downlink) Expressed in Megabits per second (Mbps), it shows the approximate downstream speed of the user's connection. The value is rounded to the nearest multiple of 25 kilobits per second. Because fingerprinting is performed again.
```
Sec-CH-ECT
```
(or ECT) stands for Valid Connection Type. Its value is one of an enumerated list of connection types, each describing a connection with RTT and downlink values in a specified range. Valid ECT values are 4g, 3g, 2g, and slow-2g.
```
Sec-CH-Prefers-Color-Scheme
```
Represents the user's favorite color scheme.
```
Sec-CH-Prefers-Reduced-Motion
```
Used to detect whether the user has asked the system to minimize the amount of animation or motion it uses.
```
Sec-CH-Prefers-Reduced-Transparency
```
Used to detect whether the user has asked the system to minimize the number of transparent or semi-transparent layer effects it uses.
```
Sec-CH-Prefers-Contrast
```
Used to detect whether the user has requested that web content be presented with a higher (or lower) contrast ratio.
```
Sec-CH-Forced-Colors
```
Used to detect whether the user agent has forced color mode enabled, in which it enforces a limited user-selected color palette on the page.