3xx Redirects
Last updated Jul 26, 2023

303 - See Other

Benjamin Bouchet
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The HTTP Status Code 303 means that the request can be found under another URI via the GET method.

What is HTTP Status Code 303?

Introduction to HTTP Status Codes

When you interact with a web application, the underlying HTTP request returns a status response code to indicate how the request was handled. These HTTP status codes are key to the Hypertext Transfer Protocol (HTTP). Among the numerous status codes, HTTP Status Code 303 holds a unique place.

Understanding HTTP Status Code 303

HTTP Status Code 303, also referred to as the HTTP response status code 'See Other', signifies that the requested resource has been temporarily moved to a new URI. This HTTP status code is used to redirect client requests to a different resource. When a server returns this status code, it also includes a location header field with the new URI.

Key Aspects of HTTP Status Code 303

In the context of HTTP status codes, a '303 See Other' status code implies that the client should attempt a new GET request on the resource specified in the location header field. This is a key distinction, as the original request could have been a POST, DELETE, or any other HTTP method.

The Semantic Web and HTTP Status Code 303

In the semantic web, HTTP status code 303 plays a critical role. This status code is used to prevent confusion between a 'real' world object and its corresponding web page. For instance, a specific car (the world object) and its corresponding web page would have different URIs, and a status code 303 can help distinguish between the two.

When and How is HTTP Status Code 303 used?

Redirection in Web Applications

HTTP status code 303 is primarily used for redirection in web applications. The HTTP status constant for '303 See Other' indicates that the web server should redirect the client request to a new resource specified in the location header field. This is particularly useful when the requested resource has moved to a new location or when the server configuration dictates a temporary redirect to a different resource.

Handling POST and DELETE Requests

HTTP status code 303 is often used in response to a POST request or a DELETE request. When a web server receives such a request, it can use the 303 status response code to indicate that the client should follow up with a new GET request. This approach effectively separates the update operation (POST or DELETE) from the retrieval request for the eventual result.

Preventing Infinite Loops

The HTTP response status code 303 can also be used to prevent infinite loops, which can occur when a user agent, like Internet Explorer, is redirected to a URL it has already requested. By specifying a new GET request to a new URI, the original target resource and the new resource are kept distinct, preventing such loops.

Role of HTTP Status Code 303 in SEO

It's important to note that search engines treat HTTP status code 303 differently than permanent redirect status codes. As a 303 status code implies a temporary redirect, search engines will typically continue to index the original target resource rather than the new location.

HTTP Status Code 303 in Python and Symfony

In Python2, the HTTP status constant for 303 is `httplib.responses[303]`. In Symfony, you would use `Symfony\Component\HttpFoundation\Response::HTTP_SEE_OTHER`.

HTTP status code 303 is truly a valuable tool in a developer's toolkit. It offers a standard method for managing redirections and is particularly helpful for maintaining a clear separation between resource manipulation and retrieval. Understanding this status code will undoubtedly aid in building more effective and efficient web applications.

Example Usage of HTTP Status Code 303

A Simple Example

To get started, let's consider a scenario where a user submits a form on a web page. Once the web server receives this HTTP request, it may need to redirect the user to a new page. Here, the HTTP status code 303, or "See Other," comes into play. It tells the user agent (such as a web browser like Internet Explorer) that it should retrieve the requested resource at a different location, using a GET retrieval request. This new location is specified in the Location header field of the HTTP response status.

This status response code is useful because it prevents the HTTP request from being repeated when the new page is refreshed. For instance, if you've ever submitted a form on a web page and then refreshed the page only to receive a warning about resubmitting form data, the web application you were using likely didn't use the 303 status code.

A More Technical Example

Now, let's dive into a more technical example, involving Python2 and Symfony. In Python, you might come across the python2 HTTP status constant for 303 in a situation like this:

from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer

class WebServerHandler(BaseHTTPRequestHandler):
    def do_POST(self):
        self.send_header('Content-type', 'text/html')
        self.send_header('Location', '/') #This will navigate to the original page

In this example, a POST request made to a certain path triggers the server to send a 303 status response code, along with a Location header that points to the homepage of the web application.

In Symfony, the HTTP status constant for 303 might be used in a context like this:

use Symfony\Component\HttpClient\HttpClient;

$client = HttpClient::create();
$response = $client->request('POST', 'http://example.com', [
    'headers' => ['Location' => '/'],

Here, a client makes a POST request to 'http://example.com'. The server then sends a 303 status code along with a Location header pointing to '/'.

What Is the History of HTTP Status Code 303?

The HTTP response status code 303, also known as "See Other," has been a part of the Hypertext Transfer Protocol (HTTP) since the release of RFC 2616, which defined HTTP 1.1. This status code provides a way to redirect web applications to a new URI, especially after a POST request has been performed.

How Does HTTP Status Code 303 Relate to Other Status Codes?

When it comes to other HTTP status codes, 303 has distinct characteristics. For example, status codes 301 and 302, while also used for redirection, have different implications.

A 301 status code, or "Permanent Redirect," advises clients to use a new URI for all future requests, essentially deeming the original target resource obsolete. It's important to use this status code with caution, as browsers and proxies tend to cache it aggressively.

On the other hand, a 302 status code, or "Found," indicates a temporary redirect. However, the implementation of this status code has been inconsistent among user agents and is generally not recommended for use. Instead, status codes 303 and 307 were introduced to replace 302, with 303 instructing the client to use a GET request for the new location, and 307 maintaining the original request method in the new request.

In comparison, the 303 status code, "See Other," is particularly useful after a POST request has been performed. It tells the client that the request has been received and processed correctly, but the resulting document should be retrieved using a GET request from the redirect URL. Unlike 301, future requests for the same resource should still go to the original URL.

Overall, understanding the nuances between different HTTP status codes, including 303, is essential for developers to ensure they are using the most appropriate response for the desired behavior. By doing so, they can improve the functionality and user experience of their web applications.

Other Intriguing Aspects of HTTP Status Code 303

Diving Deeper into Redirection

The HTTP 303 status code is a fascinating tool in the web developer's toolbox. One of its unique aspects is the way it handles redirection, particularly after an HTTP POST request. This distinguishes it from other 3xx HTTP status codes.

For instance, when you compare HTTP 303 with HTTP 301 (Permanent Redirect), a key difference surfaces. HTTP 301 signals that the requested resource has moved permanently, and future requests should use the new URL. However, aggressive caching by browsers and proxies can make this change hard to undo.

In contrast, HTTP 303 does not change the original URL for future requests, ensuring a smoother and less disruptive user experience.

Interacting with HTTP Clients

Another intriguing aspect is the role of HTTP 303 in client-server interactions. When an HTTP 303 status code is returned, it essentially instructs the client to use a GET request to retrieve the desired resource from a different URL. This is a subtle but important detail that can significantly affect how your application behaves.

A Consideration for Web Development

In web development, using Python's `BaseHTTPRequestHandler` or PHP's Symfony HttpClient, you can explicitly set HTTP 303 to redirect the client to a specified location. It's a reliable way to guide the user's journey and can be used to deliver a more controlled and predictable browsing experience.

A Thoughtful Choice Among Redirects

Between HTTP 303 and HTTP 307 (Temporary Redirect), the choice depends on the behavior you want for non-GET requests. HTTP 307 will reapply the entire original request to the new URL. However, HTTP 303 will prompt a GET request regardless of the original method.

In the HTTP status code landscape, 303 stands out with its unique properties and capabilities. It's a testament to the rich complexity of the World Wide Web, where even the most technical details can open up new possibilities for user experience and web development.

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