Via

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

Syntax

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

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

Specifications

Specification	Title
RFC 7230, section 5.7.1: Via	Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing

Browser compatibility

See also

• X-Forwarded-For
• Heroku's proxy library Vegur