Générateur de Sous-ensembles de Polices

Modern font files (OTF, TTF, WOFF, WOFF2) contain much more than letter shapes. A typical Latin font includes uppercase and lowercase letters, digits, punctuation, accented characters, ligatures, alternate glyphs, kerning pairs, and OpenType features (small caps, old-style figures, contextual alternates). A comprehensive font family can include 1,000+ glyphs. When you use a font on a website that only displays English text, you're shipping 90% of the font's data unused -- wasting bandwidth and slowing page load.

Font subsetting solves this by extracting only the glyphs you need. For an English-only website, you might need just the 95 printable ASCII characters -- reducing the font from 500 KB to 20-50 KB. For a site that uses basic Latin + common accented characters, you might need 200 glyphs. The subsetting tool uses opentype.js to parse the font's binary structure, extract the specified glyphs and their associated metrics (kerning, advance widths), and rebuild a valid font file with only those glyphs.

The WOFF2 format provides additional compression on top of subsetting. WOFF2 uses Brotli compression, which achieves 20-40% smaller files than WOFF. Modern browsers (Chrome, Firefox, Safari, Edge) all support WOFF2. The optimal approach is to subset the font to the needed glyphs, then encode it as WOFF2 for maximum compression. A 500 KB TTF font can be reduced to a 15 KB WOFF2 subset -- a 97% reduction.

For most websites, the simplest strategy is to subset to the Unicode Basic Latin range (U+0020 to U+007E), which covers all ASCII characters. This is sufficient for English content. For multilingual sites, subset to the specific Unicode ranges needed for each language and use the unicode-range CSS property to load only the relevant subset for each page. Google Fonts uses this technique -- it serves different subsets based on the page's content.

When subsetting, be careful not to remove glyphs that are referenced by OpenType features. For example, small caps feature (smcp) replaces lowercase letters with small capital versions -- if you remove the small caps glyphs, the feature will break. Our tool preserves the font's feature definitions but only includes the glyphs you specify. If you need OpenType features, include all glyphs that those features reference. For body text on the web, it's often best to disable complex OpenType features and subset to just the basic letterforms.