Headers: Via

Via header

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

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See full compatibility

The Via request and response header is added by proxies, both forward and reverse. It is used for tracking message forwards, avoiding request loops, and identifying the protocol capabilities of senders along the request/response chain.

Header type	Request header, Response header
Forbidden request header	Yes

Syntax

Via: [<protocol-name>/]<protocol-version> <host>[:<port>]
Via: [<protocol-name>/]<protocol-version> <pseudonym>

Directives

<protocol-name> Optional: The name of the protocol used, such as "HTTP".
<protocol-version>: The version of the protocol used, such as "1.1".
<host>: Public proxy URL and optional <port>. If a host is not provided, then a <pseudonym> must be used.
<pseudonym>: Name/alias of an internal proxy. If a pseudonym is not provided, then a <host> must be used.

Examples

Via: 1.1 vegur
Via: HTTP/1.1 GWA
Via: 1.0 fred, 1.1 p.example.net

Specifications

Specification
HTTP Semantics> # field.via>

Browser compatibility

	Desktop					Mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	WebView on iOS
`Via`	1	12	1	15	1	18	4	14	1	1.0	4.4	1