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<header><h1>rel=preconnect</h1></header><div class="section-content">
<p>The <code>preconnect</code> keyword for the <a href="../../element/link#rel"><code>rel</code></a> attribute of the <a href="../../element/link"><code><link></code></a> element is a hint to browsers that the user is likely to need resources from the target resource's origin, and therefore the browser can likely improve the user experience by preemptively initiating a connection to that origin. Preconnecting speeds up future loads from a given origin by preemptively performing part or all of the handshake (DNS+TCP for HTTP, and DNS+TCP+TLS for HTTPS origins).</p> <p><code><link rel="preconnect"></code> will provide a benefit to any future cross-origin HTTP request, navigation or subresource. It has no benefit on same-origin requests because the connection is already open.</p> <p>If a page needs to make connections to many third-party domains, preconnecting them all can be counterproductive. The <code><link rel="preconnect"></code> hint is best used for only the most critical connections. For the others, just use <a href="dns-prefetch"><code><link rel="dns-prefetch"></code></a> to save time on the first step — the DNS lookup.</p>
</div>
<h2 id="examples">Examples</h2>
<div class="section-content">
<div class="code-example">
<p class="example-header"><span class="language-name">html</span></p>
<pre data-signature="PYT4/2ue7hu0mrX90lIY7QK5OYVdsVtH/UE3L5jMOuA=" data-language="html"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>link</span> <span class="token attr-name">rel</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>preconnect<span class="token punctuation">"</span></span> <span class="token attr-name">href</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>https://example.com<span class="token punctuation">"</span></span> <span class="token punctuation">/></span></span>
</pre>
</div> <p>You can also implement preconnect as an HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Link">Link</a> header, for example:</p> <div class="code-example">
<p class="example-header"><span class="language-name">http</span></p>
<pre data-signature="U963iZTksn1xospr3idfnUb+T9AbbIbtg/1wWsgVgiE=" data-language="http"><span class="token header"><span class="token header-name keyword">Link</span><span class="token punctuation">:</span> <span class="token header-value"><https://example.com>; rel="preconnect"</span></span>
</pre>
</div>
</div>
<h2 id="specifications">Specifications</h2>
<div class="_table"><table class="standard-table">
<thead><tr><th scope="col">Specification</th></tr></thead>
<tbody><tr><td><a href="https://html.spec.whatwg.org/multipage/links.html#link-type-preconnect">HTML Standard <br><small># link-type-preconnect</small></a></td></tr></tbody>
</table></div>
<h2 id="browser_compatibility">Browser compatibility</h2>
<div class="_table"><table>
<thead>
<tr id="bct-browser-type">
<th></th>
<th colspan="6">Desktop</th>
<th colspan="6">Mobile</th>
</tr>
<tr id="bct-browsers">
<th></th>
<th>Chrome</th>
<th>Edge</th>
<th>Firefox</th>
<th>Internet Explorer</th>
<th>Opera</th>
<th>Safari</th>
<th>WebView Android</th>
<th>Chrome Android</th>
<th>Firefox for Android</th>
<th>Opera Android</th>
<th>Safari on IOS</th>
<th>Samsung Internet</th>
</tr>
</thead>
<tbody><tr>
<th><code>preconnect</code></th>
<td class="bc-supports-yes">46</td>
<td class="bc-supports-yes">79</td>
<td class="bc-supports-yes"><details><summary>39</summary>Before Firefox 41, it doesn't obey the <code>crossorigin</code> attribute.</details></td>
<td class="bc-supports-no">No</td>
<td class="bc-supports-yes">33</td>
<td class="bc-supports-yes">11.1</td>
<td class="bc-supports-yes">46</td>
<td class="bc-supports-yes">46</td>
<td class="bc-supports-yes"><details><summary>39</summary>Before Firefox 41, it doesn't obey the <code>crossorigin</code> attribute.</details></td>
<td class="bc-supports-yes">33</td>
<td class="bc-supports-yes">11.3</td>
<td class="bc-supports-yes">4.0</td>
</tr></tbody>
</table></div>
<h2 id="see_also">See also</h2>
<div class="section-content"><ul> <li>
<a href="https://developer.mozilla.org/en-US/docs/Web/Performance/Speculative_loading">Speculative loading</a> for a comparison of <code><link rel="preconnect"></code> and other similar performance improvement features.</li> </ul></div><div class="_attribution">
<p class="_attribution-p">
© 2005–2023 MDN contributors.<br>Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.<br>
<a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/rel/preconnect" class="_attribution-link">https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/rel/preconnect</a>
</p>
</div>
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