defconcepts / webfont-dl

Webfont Downloader

webfont-dl

Web font downloader/inliner.

Downloads a set of web fonts specified by @font-face rules in a CSS file. By default, woff equivalents are inlined as the modern browsers all support it. See the note about WOFF2 below.

By inlining woff files, this reduces the number of server roundtrips by two in the best case (the external CSS and woff files), one in the worst (just the external CSS). By reducing roundtrips we can reduce the amount of time we risk showing a flash of unstyled or hidden text content.

This tool is currently designed to work against Google's font server but should work against any hosted CSS font that uses @font-face.

But what about CDNs?

Content Distribution Networks work well in the case where you know with a high degree of certainty that a user has visited a site linking to the same piece of content. If you're using fonts that big names like Google are using (ie: Roboto) you might have a great cache hit rate. For fonts that are more "long tail" or customized via font subsetting this cache hit rate will drop off dramatically.

Google's font CDN caches the fonts themselves using a strong cache identifier: the fonts are hashed and that hash is used as a strong, long-lived cache key. The CSS that references the font, however, is only cached for a short period of time. This means that your visitors will have to frequently download the indirect CSS file, adding an extra request and latency to the page load.

By inlining the fonts in your stylesheets, you avoid the one or two extra requests that happen on cache misses. In addition, the fonts will be loaded as part of your site's CSS and you can avoid the flash of unstyled or invisible text associated with long-running font loads.

WOFF v2

The tool does not download WOFF2 files by default at this time as browser support for this is currently low and you'll lose some of the advantages of inlining a v1 woff file (for which support is very good!). You can override this behaviour using --woff2=link or --woff2=data.

Examples

Want to see it in action? Check out the test page here.

Install it globally:

npm install -g webfont-dl

Download "Crimson Text" in 400/normal and 400/italic and "Raleway" in 500/normal from Google's font API. Inlines woff (version 1) format files, puts the CSS and fonts into css/:

webfont-dl "http://fonts.googleapis.com/css?family=Crimson+Text:400,400italic|Raleway:500" \
  -o css/font.css

Download "Crimson Text" in 400/normal and 400/italic and "Raleway" in 500/normal from Google's font API. Doesn't inline any files, puts CSS into css/, and fonts in font/:

webfont-dl "http://fonts.googleapis.com/css?family=Crimson+Text:400,400italic|Raleway:500" \
  -o css/font.css --font-out=font --css-rel=../font --woff1=link

Download "Crimson Text" in 400/normal in both woff (version 1) and woff2 formats:

webfont-dl "http://fonts.googleapis.com/css?family=Crimson+Text:400 --woff1=link --woff2=link

Download the OpenSans collection from github:

webfont-dl -d "https://github.com/steakejjs/OpenSans-CSS/raw/master/OpenSans.css" \
  -o css/font.css --font-out=font --css-rel=../font

Output

The CSS output from the tool contains a number of features:

• The fonts are strongly named using a sha-1 hash
• local() names are preserved from the input CSS
• IE6-8 compatibility is enabled by hoisting a copy of eot files into a separate src: line
• Selected font formats are inlined

Example output:

@font-face {
  font-family: 'Crimson Text';
  font-style: normal;
  font-weight: 400;
  /* IE6-8 compat */
  src: url("/font/crimsontext-5a145c6f1863c2b986e33b7172a7059e4c6557dd.eot");
  src: local("Crimson Text"), 
    local("CrimsonText-Roman"), 
    url("data:application/font-woff;base64,...") format("woff"), 
    url("/font/crimsontext-5a145c6f1863c2b986e33b7172a7059e4c6557dd.eot") format("embedded-opentype"), 
    url("/font/crimsontext-528b74b55df7980a8f694e9a56d2feeaa1ae351e.svg#CrimsonText") format("svg"), 
    url("/font/crimsontext-381297740916b3fe12a631447ee8a802af3bea16.ttf") format("truetype");
}

Usage

Web font downloader.

Given a font definition file in webfontloader style, outputs a single CSS file
and downloaded fonts in a given output directory.

Usage: webfont <css-url-or-file> --out FILE [options]

--help,-h           Prints help
--out FILE,-o FILE  Output file for CSS
--font-out=DIR      Font output directory [default: same folder as CSS]
--css-rel=PATH      CSS-relative path for fonts [default: ./]
--woff2=<mode>      Processing mode for woff v2 fonts: data, link or omit [default: omit]
--woff1=<mode>      Processing mode for woff v1 fonts: data, link or omit [default: data]
--svg=<mode>        Processing mode for svg fonts: data, link or omit [default: link]
--ttf=<mode>        Processing mode for ttf fonts: data, link or omit [default: link]
--eot=<mode>        Processing mode for eot fonts: data, link or omit [default: link]
-d                  Debug info [default: false]