Was spelunking in the folders of my Visual Studio 11 installation a couple of weeks ago and found Microsoft.CSS.Core.dll (located in C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\CommonExtensions\Microsoft\Web\CSS3).

I was intrigued and needed to look deeper and what I found was a CSS parser that you can use from your application e.g. I needed a CSS unpacker (that turns a minimized CSS file into a readable format). With the built in formatter I was able to do this:

static void Main(string[] args)
{
    if (args.Length < 2)
    {
        Console.WriteLine("cssunpack [input] [output]");
        Environment.Exit(-1);
    }

    var parser = new CssParser();

    var css = parser.Parse(File.ReadAllText(args[0]),
                            insertComments: false);

    var formatter = new CssFormatter();
    File.WriteAllText(args[1], formatter.Format(css));
}

So if we do some small tweaks to the CssFormatterOptions we can build a minimizer as well:

static void Main(string[] args)
{
    if (args.Length < 2)
    {
        Console.WriteLine("csspack [input] [output]");
        Environment.Exit(-1);
    }

    var parser = new CssParser();

    var css = parser.Parse(File.ReadAllText(args[0]),
                            insertComments: false);

    var formatter = new CssFormatter
    {
        Options = new CssFormattingOptions
        {
            IndentType = IndentType.Spaces,
            IndentSize = 0,
            SpacesPerTab = 0,
            InitialIndentString = string.Empty,
            QuoteType = QuoteType.Double,
            BlockBracePosition = BracePosition.Compact,
            SortProperties = false,
            CompactBlocks = false,
            CompactBlockThreshold = 0,
            RemoveEscapes = true,
            ConvertColorsToHex = true,
            CompressColors = true,
            ElementSelectorCasing = Casing.Lowercase,
            PropertyNameCasing = Casing.Lowercase,
            RemoveLastSemicolon = true,
            IndentRuleHierarchy = false,
            ForStyleBlock = true
        }
    };
    File.WriteAllText(args[1], formatter.Format(css).Replace(Environment.NewLine, ""));
}

There is a lot of more features so take a look for yourself.

I don’t know about the license but it’s probably ok to use on your local dev machine if you have VS11 installed.