Netlify Subfont Build Plugin

Subfont post-processes your web page to analyse you usage of web fonts, then reworks your webpage to use an optimal font loading strategy for the best performance. It will also aggressively subset your fonts to speed up the time to font download.

Subfont will generate some new files, fonts and CSS, and will add immutavble cache headers for them automatically.

See Peter Müller's presentation of Subfont at Fronteers 2019.

Subfont is compatible with Google Fonts and local fonts.

Installation

To install, add the following lines to your netlify.toml file:

[[plugins]]
package = "netlify-plugin-subfont"

Note: The [[plugins]] line is required for each plugin, even if you have other plugins in your netlify.toml file already.

If you are using local fonts from your own repository it is recommended to also install fonttools. On Netlify you can do this by adding the following content into requirements.txt in your project root:

fonttools
brotli
zopfli

Configuration

Subfont works out of the box, but can be improved upon with some improved knowledge about your site.

These are the configuration options with their default values:

[[plugins]]
package = "netlify-plugin-subfont"

  [plugins.inputs]
  # An array of glob patterns for pages on your site
  # Recursive traversal will start from these
  entryPoints = [
    "*.html",
  ]

  # Follow your links across all pages to optimize the fonts across the antire site
  recursive = true

  # Subfont lets you set CSS font-display value of the optimized subsets
  # See https://developer.mozilla.org/en-US/docs/Web/CSS/@font-face/font-display
  fontDisplay = "swap"

  # Inline generated CSS @font-face blocks into each page
  # When set to `false` an external CSS file will be created
  inlineCss = false

  # Inline generated font subsets into their respective @font-face blocks
  # When set to `false` external font files will be created
  inlineFonts = false