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 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 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>-
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
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