Break free from CSS prefix hell!

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-prefix-free lets you use only unprefixed CSS properties everywhere. It works behind the scenes, adding the current browser’s prefix to any CSS code, only when it’s needed.

“[-prefix-free is] fantastic, top-notch work! Thank you for creating and sharing it.”

Eric Meyer




Check this page’s stylesheet ;-)

You can also visit the Test Drive page, type in any code you want and check out how it would get prefixed for the current browser.

How to use

Just include prefixfree.js anywhere in your page. It is recommended to put it right after the stylesheets, to minimize FOUC

That’s it, you’re done!

Browser support

The target browser support is IE9+, Opera 10+, Firefox 3.5+, Safari 4+ and Chrome on desktop and Mobile Safari, Android browser, Chrome and Opera Mobile on mobile.

If it doesn’t work in any of those, it’s a bug so please report it. Just before you do, please make sure that it’s not because the browser doesn’t support a CSS3 feature at all, even with a prefix.

In older browsers like IE8, nothing will break, just properties won’t get prefixed. Which wouldn’t be useful anyway as IE8 doesn’t support much CSS3 ;)

Test drive

Test the prefixing that -prefix-free would do for this browser, by writing some CSS below:


What if I actually want to target only a specific prefix?

Properties/values etc that already have a prefix won’t be altered. However, if you use the unprefixed property/value etc after the prefixed properties, you might run into issue #16. For those cases, -prefix-free adds a class on the root element (the <html> element in HTML) with the same name as the current prefix. So for example, to solve the problem presented in the above issue, you could do:

.myselector {
    transform: rotate(15deg);
.-webkit- .myselector {
    transform: rotate(15deg) rotateX(0);

It’s not ideal, but it’s a solution, until a more intuitive way to deal with these cases is added in -prefix-free.

Please note that in unsupported browsers like IE8, no such class will be added.

How do I exclude specific files from being prefixed?

You can exclude a file from being prefixed by adding the data-noprefix attribute to the <link> or <style> element. For example:

<link href="//example.com/style.css" rel="stylesheet" type="text/css" data-noprefix>

How do I enable local testing?

Firefox (and IE?) natively support local XHR, so -prefix-free will work fine locally with them.

To enable local XHR for Chrome, you need to run it with the flag --allow-file-access-from-files.

To enable local XHR for Opera, you have to go to opera:config#UserPrefs|AllowFileXMLHttpRequest, check that option and Save.

Something like this belongs to the server-side

A server side script would need to add all prefixes, making the size of the CSS file considerably larger. Also, it should maintain a list of features that need prefixes, or add them all and unnecessarily bloat the stylesheet. -prefix-free automatically detects what needs a prefix and what doesn’t.

Also, a common argument against doing this on the client side, is that it makes the design rely on JavaScript. However, that is completely false: If JS is disabled, only some of the CSS3 won’t show. But if your design relies on CSS3 to be functional, you have bigger problems bro.

You can read some more about this in my recent CSS Tricks interview

But every solution has its own pros and cons. If you would feel more comfortable with a server-side script, use that and don’t troll me please. Remember: nobody forced you to use -prefix-free. KTHXBAI ☺


Extra code on top of -prefix-free that makes it more flexible, integrates it with different APIs etc

Dynamic DOM plugin

Originally a part of -prefix-free, it’s now a separate plugin. It makes -prefix-free take care of:

Things to be aware of:

Get the Dynamic DOM plugin now:

jQuery plugin

A tiny plugin (I didn’t even bother minifying it as it’s so small) that lets you set/get unprefixed CSS properties through jQuery's .css method.

Get the jQuery plugin now:

Viewport-relative units

A static polyfill for the new vw, vh, vmin, vmax units.

CSS Variables

Enables rudimentary CSS variables support.