Via

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.

The Via general header is added by proxies, both forward and reverse, and can appear in the request or response headers. 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 header name yes

Syntax

http
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> and <port>

Public proxy URL and port.

<pseudonym>

Name/alias of an internal proxy.

Examples

http
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

BCD tables only load in the browser

See also