How to save up another precious HTTP-request for the tiny favicon?

Question

Everybody knows how to set up a favicon.ico link in their HTML:

<link rel="shortcut icon" href="http://hi.org/icon.ico" type="image/x-icon">

But it's silly that for only a several-byte-tiny icon we need yet yet another potentially speed-penalizing HTTP request.

So I wondered, how could I make that favicon part of a usable sprite (e.g., background-position=0px -200px;) that doubles as, say, a logo on the rest of the website, in order to speed up the site and save that precious and valuable HTTP request. How can we get this to go into an existing sprite image along with our logo and other artworks?

Answer 1

Killer Solution in 2020

This solution necessarily comes nine years after the question was originally asked, because, until fairly recently, most browsers have not been able to handle favicons in .svg format.

That's not the case anymore.

See: https://caniuse.com/#feat=link-icon-svg

---

1) Choose SVG as the Favicon format

Right now, in June 2020, these browsers can handle SVG Favicons:

• Chrome
• Firefox
• Edge
• Opera
• Chrome for Android
• KaiOS Browser

Note that these browsers still can't:

• Safari
• iOS Safari
• Firefox for Android

Nevertheless, with the above in mind, we can now use SVG Favicons with a reasonable degree of confidence.

---

2) Present the SVG as a Data URL

The main objective here is to avoid HTTP Requests.

As other solutions on this page have mentioned, a pretty smart way to do this is to use a Data URL rather than an HTTP URL.

SVGs (especially small SVGs) lend themselves perfectly to Data URLs, because the latter is simply plaintext (with any potentially ambiguous characters percentage-encoded) and the former, being XML, can be written out as a long line of plaintext (with a smattering of percentage codes) incredibly straightforwardly.

---

3) The entire SVG is a single Emoji

N.B. This step is optional. Your SVG can be a single emoji, but it can just as easily be a more complex SVG.

In December 2019, Leandro Linares was one of the first to realise that since Chrome had joined Firefox in supporting SVG Favicons, it was worth experimenting to see if a favicon could be created out of an emoji:

https://lean8086.com/articles/using-an-emoji-as-favicon-with-svg/

Linares' hunch was right.

Several months later (March 2020), Code Pirate Lea Verou realised the same thing:

https://twitter.com/leaverou/status/1241619866475474946

And favicons were never the same again.

---

4) Implementing the solution yourself:

Here's a simple SVG:

<svg
  xmlns="http://www.w3.org/2000/svg"
  viewBox="0 0 16 16">

  <text x="0" y="14">🦄</text>
</svg>

And here's the same SVG as a Data URL:

data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2016%2016'%3E%3Ctext%20x='0'%20y='14'%3E🦄%3C/text%3E%3C/svg%3E

And, finally, here's that Data URL as a Favicon:

<link rel="icon" href="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2016%2016'%3E%3Ctext%20x='0'%20y='14'%3E🦄%3C/text%3E%3C/svg%3E" type="image/svg+xml" />

---

5) More tricks (...these are not your parents' favicons!)

Since the Favicon is an SVG, any number of filter effects (both SVG and CSS) can be applied to it.

For instance, alongside the White Unicorn Favicon above, we can easily make a Black Unicorn Favicon by applying the filter:

style="filter: invert(100%);"

Black Unicorn Favicon:

<link rel="icon" href="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2016%2016'%3E%3Ctext%20x='0'%20y='14'%20style='filter:%20invert(100%);'%3E🦄%3C/text%3E%3C/svg%3E" type="image/svg+xml" />

Answer 2

I think for the most part it does not result in another HTTP request as these are usually dumped in the browser's cache after the first access.

This is actually more efficient than any of the proposed "solutions".

Answer 3

A minor improvement to @yc's answer is injecting the Base64-encoded favicon from a JavaScript file that would normally be used and cached anyway, and also suppressing the standard browser behavior of requesting favicon.ico by feeding it a data URI in the relevant meta tag.

This technique avoids the extra http request and is confirmed to work in recent versions of Chrome, Firefox and Opera on Windows 7. However it doesn't appear to work in Internet Explorer 9 at least.

File index.html

<!doctype html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <!-- Suppress browser request for favicon.ico -->
        <link rel="shortcut icon"type="image/x-icon" href="data:image/x-icon;,">
        <script src="script.js"></script>
...

File script.js

var favIcon = "\
iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAABrUlEQVR42mNkwAOepOgxMTD9mwhk\
[...truncated for brevity...]
IALgNIBUQBUDAFi2whGNUZ3eAAAAAElFTkSuQmCC";

var docHead = document.getElementsByTagName('head')[0];
var newLink = document.createElement('link');
newLink.rel = 'shortcut icon';
newLink.href = 'data:image/png;base64,'+favIcon;
docHead.appendChild(newLink);

/* Other JavaScript code would normally be in here too. */

Demo: turi.co/up/favicon.html

Answer 4

You could try a data URI. No HTTP request!

<link id="favicon" rel="shortcut icon" type="image/png" href="data:image/png;base64,....==">

Unless your pages have static caching, your favicon wouldn't be able to be cached, and depending on the size of your favicon image, your source code could get kind of bloated as a result.

Data URI favicons seems to work in most modern browsers; I have it working in recent versions of Chrome, Firefox and Safari on a Mac. Doesn't seem to work in Internet Explorer, and possibly some versions of Opera.

If you're worried about old Internet Explorer versions (and you probably shouldn't be these days), you could include an Internet Explorer conditional comment that would load the actual favicon.ico in the traditional way, since it seems that older Internet Explorer doesn't support data URI favicons.

`<!--[if IE ]><link rel="shortcut icon" href="http://example.com/favicon.ico"  type="image/x-icon" /><![endif]--> `

2. Include the favicon.ico file in your root directory to cover browsers that will request it either way, since for those browsers, if they're already checking no matter what you do, you might as well not waste the HTTP request with a 404 response.

You could also just use the favicon of another popular site which is likely to have their favicon cached, like http://google.com/favicon.ico, so that it is served from cache.

As commenters have pointed out, just because you can do this doesn't mean you should, since some browsers will request favicon.ico regardless of the tricks we devise. The amount of overhead you'd save by doing this would be minuscule compared to the savings you'd get from doing things like gzipping, using far-future expires headers for static content, minifying JavaScript files, putting background images into sprites or data URIs, serving static files off of a CDN, etc.

Answer 5

You could use a Base64-encoded favicon, like:

<link href="data:image/x-icon;base64,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" rel="icon" type="image/x-icon" />

Answer 6

I found an interesting solution on this page. It is in German, but you will be able to understand the code.

You put the base64 data of the icon into an external style sheet, so it will be cached. In the head of your website you have to define the favicon with an id and the favicon is set as a background-image in the style sheet for that id.

link#icon {
    background-image:url("data:image/x-icon;base64,<base64_image_data>");
}

and the html

<html>
    <head>
        <link id="icon" rel="shortcut icon" type="image/x-icon" />
        <link rel="stylesheet" type="text/css" href="/styles.css" />
        ...
    </head>
    <body>
        ...
    </body>
</html>

Answer 7

Good point and nice idea, but impossible. A favicon needs to be a single, separate resource. There is no way to combine it with another image file.

Answer 8

Does it really matter?

Many browsers load the favicon as a low priority so that it doesn't block the page load in anyway, so yes it's an extra request, but it's not on any critical path.

The accepted solution is horrible as until the JavaScript code has been retrieved and executed, all the DOM elements below will be blocked from rendering and it doesn't reduce the number of requests!

Answer 9

The proper solution is to use HTTP pipelining.

HTTP pipelining is a technique in which multiple HTTP requests are written out to a single socket without waiting for the corresponding responses. Pipelining is only supported in HTTP/1.1, not in 1.0.

It's required that servers support it, but not necessarily participate.

HTTP pipelining requires both the client and the server to support it. HTTP/1.1 conforming servers are required to support pipelining. This does not mean that servers are required to pipeline responses, but that they are required not to fail if a client chooses to pipeline requests.

Many browser clients don't do it, when they should.

HTTP pipelining is disabled in most browsers.

• Opera has pipelining enabled by default. It uses heuristics to control the level of pipelining employed depending on the connected server.
• Internet Explorer 8 does not pipeline requests, due to concerns regarding buggy proxies and head-of-line blocking.
• Mozilla browsers (such as Mozilla Firefox, SeaMonkey and Camino), support pipelining however it is disabled by default. It uses some heuristics, especially to turn pipelining off for IIS servers.
• Konqueror 2.0 supports pipelining, but it's disabled by default.[citation needed]
• Google Chrome does not support pipelining.

I would recommend you try enabling pipelining in Firefox and try it there, or just use Opera (shudder).

Answer 10

This is not really an answer to the question, but simply to compliment the answers given by Marcel and yahelc. I offer an elegant solution to the 404 favicon issue.

Some applications and browsers check for a favicon.ico file and if the icon is not found in the site root, you can simply respond to the request with the 204 response header.

Apache Examples:

Apache option one (and my favorite), a simple one-liner in your .htacces or .conf:

Redirect 204 /favicon.ico

Apache option two:

<Files "favicon.ico">
    ErrorDocument 204 ""
</Files>

For further reading there is a nice blog post by Stoyan Stefanov.

Answer 11

It's a great idea, but if Google hasn't done it on their homepage, I'm betting it can't (currently) be done.

Answer 12

I'm sorry, but you can't combine the favicon with another resource.

This means you have basically two options:

1. If you're comfortable with your site not having a favicon - you can just have the href point to a non-icon resource that is already being loaded (e.g., a style sheet, script file, or even some resource that benefits from being pre-fetched). (My brief testing indicates that this works across most, if not all, major browsers.)

2. Accept the extra HTTP request and just make sure your favicon file has aggressive HTTP cache-control headers set. (If you have other websites under your control, you might even have them sneakily preload the favicon for this website - along with other static resources.)

P.S. Creative solutions that will not work:

• The weird CSS data URI trick (linked to by commenter Felix Geenen) does not work.
• Using JavaScript to perform a delayed injection of the favicon <link> element (as suggested by user yc) will likely just make things worse - by resulting in two HTTP requests.

Answer 13

Here's the easiest way:

<!DOCTYPE html><html><head> 
<link rel="shortcut icon" href="data:image/png;base64,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">
</head></html> 

What icon does it represent? Answer below!

Answer 14

You can use an 8-bit PNG image instead of the ICO format for an even smaller data footprint. The only thing you have to change is using "data:image/png" instead of "data:image/x-icon" MIME type header:

<link
  href="data:image/png;base64,your-base64-encoded-string-goes-here"
  rel="icon" type="image/png"
/>

"type" attribute can be "image/png" or "image/x-icon". Both work for me.

You can convert ICO to 8-bit PNG using GIMP or convert:

convert favicon.ico -depth 8 -strip favicon.png

And encode the PNG binary to a Base64-string using the base64 command:

base64 favicon.png