300 Multiple Choices

The HTTP 300 Multiple Choices redirection response status code indicates that the request has more than one possible response. The user-agent or the user should choose one of them.

Note: In Transparent Content Negotiation (TCN), a client and server collaboratively decide the best variant of a given resource when the server has multiple variants. Most modern browsers have poor support due to complexity in implementations, lack of standardization of how clients automatically choose from responses, and the additional round-trips that slow down client-server interaction. Server-driven content negotiation is far more common, where a server chooses the most appropriate resource for the client based on the request headers (Accept-Language, Accept, etc.).

The server should include content in the response that contains a list of resource metadata and URIs from which the user or user agent can choose. The format of the content is implementation-specific, but should be easily parsed by the user agent (such as HTML or JSON).

If the server has a preferred choice that the client should request, it can include it in a Location header.

Status

http
300 Multiple Choices

Examples

300 response with list of resources

The following example demonstrates a Transparent Content Negotiation request-response exchange. An Apache server offers multiple variants of a resource defined in a type map; index.html.en for a resource in English, and index.html.fr for a French version: 

URI: index.html.en
Content-Language: en

URI: index.html.fr
Content-Language: fr

A Negotiate: trans request header indicates that the client wants to use TCN to choose a resource. Poor browser support for this mechanism means a user agent such as curl must be used instead:

bash
 curl -v -H "Negotiate: trans" http://localhost/index

This produces the following request:

http
GET /index HTTP/1.1
Host: localhost
User-Agent: curl/8.7.1
Accept: */*
Negotiate: trans

We receive a 300 response with details of different representations of the requested resource:

http
HTTP/1.1 300 Multiple Choices
Date: Fri, 30 Aug 2024 09:21:48 GMT
Server: Apache/2.4.59 (Unix)
Alternates: {"index.html.en" 1 {type text/html} {language en} {length 48}}, {"index.html.fr" 1 {type text/html} {language fr} {length 45}}
Vary: negotiate,accept-language
TCN: list
Content-Length: 419
Content-Type: text/html; charset=iso-8859-1

<html><head>
<title>300 Multiple Choices</title>
</head><body>
<h1>Multiple Choices</h1>
Available variants:
<ul>
<li><a href="index.html.en">index.html.en</a> , type text/html, language en</li>
<li><a href="index.html.fr">index.html.fr</a> , type text/html, language fr</li>
</ul>
</body></html>

Specifications

Specification
HTTP Semantics
# status.300

See also