Revision 1107727 of 304 Not Modified

<div>{{HTTPSidebar}}</div>

<p>The HTTP <code><strong>304</strong></code><strong><code> Not Modified</code></strong> client redirection response code indicates that there is no need to retransmit the requested resources. It is an implicit redirection to a cached resource. This happens when the request method is {{glossary("safe")}}, like a {{HTTPMethod("GET")}} or a {{HTTPMethod("HEAD")}} request, or when the request is conditional and uses a {{HTTPHeader("If-None-Match")}} or a {{HTTPHeader("If-Modified-Since")}} header.</p>

<p>If the equivalent {{HTTPStatus("200")}} <code>OK</code> response would have included the headers {{HTTPHeader("Cache-Control")}}, {{HTTPHeader("Content-Location")}}, {{HTTPHeader("Date")}}, {{HTTPHeader("ETag")}}, {{HTTPHeader("Expires")}}, and {{HTTPHeader("Vary")}}.</p>

<div class="note">
<p>Many <a href="/en-US/docs/Tools/Network_Monitor">developer tools' network panels</a> of browsers create extraneous requests leading to <code>304</code> responses, so that access to the local cache is visible to developers.</p>
</div>

<h2 id="Status">Status</h2>

<pre class="syntaxbox">
304 Not Modified</pre>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Title</th>
  </tr>
  <tr>
   <td>{{RFC("7232", "304 Not Modified" , "4.1")}}</td>
   <td>Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<p class="hidden">The compatibility table in this page is generated from structured data. If you’d like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data/README.md">https://github.com/mdn/browser-compat-data/README.md</a> and send us a pull request.</p>

<p>{{Compat}}</p>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{HTTPHeader("If-Modified-Since")}}</li>
 <li>{{HTTPHeader("If-None-Match")}}</li>
</ul>