Autoprefixer

Parse CSS and add vendor prefixes to CSS rules using values from Can I Use.

Write your CSS rules without vendor prefixes (in fact, forget about them entirely):

:fullscreen a {
    transition: transform 1s;
}

Autoprefixer will use the data based on current browser popularity and property support to apply prefixes for you. You try in the interactive demo of Autoprefixer.

:-webkit-full-screen a {
    -webkit-transition: -webkit-transform 1s;
            transition: transform 1s;
}
:-moz-full-screen a {
    transition: transform 1s;
}
:-ms-fullscreen a {
    transition: transform 1s;
}
:fullscreen a {
    -webkit-transition: -webkit-transform 1s;
            transition: transform 1s;
}

Twitter account for news and releases: @autoprefixer.

Sponsored by Evil Martians. Based on PostCSS framework.

Features

Write Pure CSS

Working with Autoprefixer is simple: just forget about vendor prefixes and write normal CSS according to the latest W3C specs. You don’t need a special language (like Sass) or remember, where you must use mixins.

Autoprefixer supports selectors (like :fullscreen and ::selection), unit function (calc()), at‑rules (@support and @keyframes) and properties.

Because Autoprefixer is a postprocessor for CSS, you can also use it with preprocessors such as Sass, Stylus or LESS.

Flexbox, Filters, etc.

Just write normal CSS according to the latest W3C specs and Autoprefixer will produce the code for old browsers.

a {
    display: flex;
}

compiles to:

a {
    display: -webkit-box;
    display: -webkit-flex;
    display: -moz-box;
    display: -ms-flexbox;
    display: flex
}

Autoprefixer has 22 special hacks to fix web browser differences.

Only Actual Prefixes

Autoprefixer utilizes the most recent data from Can I Use to add only necessary vendor prefixes.

It also removes old, unnecessary prefixes from your CSS (like border-radius prefixes, produced by many CSS libraries).

a {
    -webkit-border-radius: 5px;
            border-radius: 5px;
}

compiles to:

a {
    border-radius: 5px;
}

Browsers

You can specify the browsers you want to target in your project:

• last 2 versions targets the last 2 versions for each browser..
• last 2 Chrome versions targets the last versions of a specific browser.
• > 5% declares browser versions selected by global usage statistics.
• Firefox > 20 targets versions of Firefox newer than 20.
• Firefox >= 20 targets versions of Firefox newer than or equal to 20.
• Firefox < 20 targets versions of Firefox less than 20.
• Firefox <= 20 targets versions of Firefox less than or equal to 20.
• Firefox ESR specifies the latest Firefox ESR version.
• ios 7 will set the browser version directly.
• none will not target any browsers.

Blackberry and stock Android browsers will not be used in last n versions. You should add them by name.

Browsers names (case insensitive):

• Android for old Android stock browser.
• BlackBerry or bb for Blackberry browser.
• Chrome for Google Chrome.
• Firefox or ff for Mozilla Firefox.
• Explorer or ie for Internet Explorer.
• iOS or ios_saf for iOS Safari.
• Opera for Opera.
• Safari for desktop Safari.
• OperaMobile or op_mob for Opera Mobile.
• OperaMini or op_mini for Opera Mini.
• ChromeAndroid or and_chr for Chrome for Android (mostly same as common Chrome).
• FirefoxAndroid or and_ff for Firefox for Android.
• ExplorerMobile or ie_mob for Internet Explorer Mobile.

By default, Autoprefixer uses > 1%, last 2 versions, Firefox ESR, Opera 12.1:

• Latest Firefox ESR is a 24 version.
• Opera 12.1 will be in list until Opera supports non-Blink 12.x branch.

Source Map

Autoprefixer can modify previous source maps (for example, from Sass): it will autodetect a previous map if it is listed in an annotation comment.

Autoprefixer supports inline source maps too. If an input CSS contains annotation from the previous step with a map in data:uri, Autoprefixer will update the source map with prefix changes and inline the new map back into the output CSS.

Visual Cascade

Autoprefixer changes CSS indentation to create a nice visual cascade of prefixes if the CSS is uncompressed:

a {
    -webkit-box-sizing: border-box;
       -moz-box-sizing: border-box;
            box-sizing: border-box;
}

You can disable cascade by using the cascade: false option.

Disabling

Autoprefixer was designed to have no interface – it just works. If you need some browser specific hack just write prefixed property after unprefixed.

a {
    transform: scale(0.5);
    -moz-transform: scale(0.6);
}

If some prefixes were generated in wrong way, please create issue on GitHub.

But if you do not need Autoprefixer in some part of your CSS, you can use control comments to disable Autoprefixer.

a {
    transition: 1s; /* it will be prefixed */
}

b {
    /* autoprefixer: off */
    transition: 1s; /* it will not be prefixed */
}

Control comments disables Autoprefixer within the whole rule in which you place it. In the above example, Autoprefixer will be disabled in the entire b rule scope, not only after the comment.

You can also use comments recursively:

/* autoprefixer: off */
@support (transition: all) {
    /* autoprefixer: on */
    a {
        /* autoprefixer: off */
    }
}

FAQ

Does it add polyfills for old browsers?

No. Autoprefixer only adds prefixes, not polyfills. There are two reasons:

1. Prefixes and polyfills are very different and need a different API. Two separate libraries would be much better.
2. Most of IE polyfills are bad for client performance, as they use slow hacks and old IEs often runs on old hardware. Most CSS3 features used only for styling should be ignored in old IEs as it is recommended for graceful degradation.

Why doesn’t gradients work in Firefox?

Make sure that you use correct the direction syntax. For example, you should use to bottom instead of top:

a {
  background: linear-gradient(to bottom, white, black)
}

Unfortunately, unprefixed gradients use a different direction syntax and most examples you find use an old gradient syntax, so be careful and use always the latest W3C specs with Autoprefixer.

Why doesn’t Autoprefixer add prefixes to border-radius?

Developers are often surprised by how few prefixes are required today. If Autoprefixer doesn’t add prefixes to your CSS, check if they’re still required on Can I Use.

Why doesn’t Autoprefixer support appearance?

Unlike transition, the appearance property is not a part of any specification. So there is no appearance, only -moz-appearance and -webkit-appearance.

Usage

Grunt

You can use the grunt-autoprefixer plugin for Grunt. Install the npm package and add it to Gruntfile:

grunt.loadNpmTasks('grunt-autoprefixer');

Gulp

In Gulp you can use gulp-postcss with autoprefixer-core npm package.

gulp.task('autoprefixer', function () {
    var postcss      = require('gulp-postcss');
    var sourcemaps   = require('gulp-sourcemaps');
    var autoprefixer = require('autoprefixer-core');

    return gulp.src('./src/*.css')
        .pipe(sourcemaps.init())
        .pipe(postcss([autoprefixer]))
        .pipe(sourcemaps.write('.'))
        .pipe(gulp.dest('./dest'));
});

With gulp-postcss you also can combine Autoprefixer with other PostCSS plugins.

Other Build Tools:

• Ruby on Rails: autoprefixer-rails
• Webpack: autoprefixer-loader
• Brunch: autoprefixer-brunch
• Broccoli: broccoli-autoprefixer
• Middleman: middleman-autoprefixer
• Mincer: add autoprefixer npm package and enable it: environment.enable('autoprefixer').

Compass

If you use Compass binary to compile your styles, you can easily integrate Autoprefixer with it. Install autoprefixer-rails gem:

gem install autoprefixer-rails

and add post-compile hook to config.rb:

require 'autoprefixer-rails'

on_stylesheet_saved do |file|
  css = File.read(file)
  File.open(file, 'w') do |io|
    io << AutoprefixerRails.process(css)
  end
end

You can set the browsers option as the second argument in process method.

Stylus

If you use Stylus CLI, you can add Autoprefixer by autoprefixer-stylus plugin:

stylus -u autoprefixer-stylus -w file.styl

CodeKit

CodeKit, since the 2.0 version, contains Autoprefixer. In the After Compiling section, there is a checkbox to enable Autoprefixer. Read CodeKit docs for more inforamtion.

Prepros

If you need free assets build GUI tool, try Prepros. Just set “Auto Prefix CSS” checkbox in right panel.

CLI

You can use the autoprefixer binary to process CSS files using any assets manager:

sudo npm install --global autoprefixer
autoprefixer *.css

See autoprefixer -h for help.

JavaScript

You can use autoprefixer-core in your node.js application or if you want to develop Autoprefixer plugin for new environment.

var autoprefixer = require('autoprefixer-core');
var prefixed     = autoprefixer.process('a { transition: transform 1s }').css;

Autoprefixer can be also used as a PostCSS processor, so you can combine it with other processors and parse CSS only once:

postcss().
    use( autoprefixer({ browsers: ['> 1%', 'IE 9'] }) ).
    use( compressor ).
    process(css);

There is also standalone build for the browser or as a non-Node.js runtime.

PHP

You can use Autoprefixer in PHP by autoprefixer-php library:

$autoprefixer = new Autoprefixer();
$prefixed     = $autoprefixer->compile('a { transition: transform 1s }');

.NET

For .NET you can use Autoprefixer for .NET library.

For ASP.NET you can use the official BundleTransformer.Autoprefixer plugin for Bundle Transformer.

1. Install package via NuGet:

PM> Install-Package BundleTransformer.Autoprefixer

2. Perform a post-install actions specified in the readme.txt file.
3. Register a bundles in the App_Start/BundleConfig.cs file and configure the Bundle Transformer (see the documentation).

Text Editors

Autoprefixer should be used in assets build tools. Text editor plugins are not a good solution, because prefixes decrease code readability and you will need to change value in all prefixed properties.

I recommend you to learn build tools like Grunt or Gulp. They works much better and will open you entire new world of useful plugins and automatization.

But, if you can’t move to build tool, you can use text editor plugins:

• Sublime Text
• Brackets
• Atom Editor

Visual Studio

You can apply the Autoprefixer optimizations to your LESS/Sass stylesheets in Visual Studio 2013 by using the Web Essentials 2013 plugin (since the 2.2 version).

To add this functionality in the Visual Studio 2013 (Update 2 or later) you need to do the following steps:

1. Download and install the Web Essentials 2013 for Update 2.
2. Choose a Tools → Options → Web Essentials → CSS menu item
3. In the Enable Autoprefixer box specify a value equal to True