Extract glyphs from fonts and generate optimized, minimal font files.

Two engines for different use cases:

• Icon engine — extract glyphs from ligature-based icon fonts (Material Icons, etc.)
• Subset engine — subset any font by characters or unicode ranges, preserving kerning and OpenType features

Why Fontext?

Icon fonts often contain 1000+ glyphs. Text fonts ship entire alphabets when you only need a subset. Fontext solves both:

• Extract by ligature — pass ligature names like "home", "search", "menu" (icon engine)
• Extract by raw unicode — pass the actual unicode character and Fontext resolves the ligature automatically (icon engine)
• Subset by characters — pass "ABCabc0123" to keep only those characters (subset engine)
• Subset by unicode range — pass U+0400-U+04FF for Cyrillic block (both engines)
• Multiple output formats — SVG, TTF, WOFF, WOFF2, EOT
• Preserves font features — subset engine keeps kerning, hinting, GSUB/GPOS via HarfBuzz
• Glyph metadata — get name, unicode mappings, and SVG path data for each extracted glyph

Installation

npm install fontext

CLI

npx fontext -i material-icons.woff2 -n my-icons -l home,search,menu -f woff2,ttf -o ./fonts

| Flag | Description | |-------------------------|---------------------------------------------------------| | -i, --input | Path to the font file (required) | | -n, --font-name | Name for the output font (required) | | -l, --ligatures | Comma-separated ligature names | | -r, --raws | Comma-separated raw unicode characters | | -u, --unicode-ranges | Comma-separated unicode ranges (e.g. U+E000-U+E100) | | -f, --formats | Output formats: svg,ttf,woff,woff2,eot (default: all) | | -o, --output | Output directory (default: .) | | -w, --with-whitespace | Include whitespace glyph |

Quick Start

import {extract} from 'fontext';
import fs from 'fs';

const font = fs.readFileSync('material-icons.woff2');

const result = await extract(font, {
    fontName: 'my-icons',
    ligatures: ['home', 'search', 'menu'],
    formats: ['woff2', 'ttf'],
});

// result.woff2 — Buffer with optimized WOFF2 font
// result.ttf  — Buffer with optimized TTF font
// result.meta — glyph metadata (name, unicode, svg)

fs.writeFileSync('my-icons.woff2', result.woff2);

API

extract(content, options): Promise<ExtractedResult>

| Parameter | Type | Description | |-----------|----------------|---------------------------------------------------------------------| | content | Buffer | Font file contents (TTF, WOFF2, or any format supported by fontkit) | | options | MinifyOption | Extraction configuration (see below) |

MinifyOption

| Field | Type | Default | Description | |------------------|-------------|-------------|-----------------------------------------------------------------------------| | fontName | string | — | Required. Name for the output font | | ligatures | string[] | [] | Ligature strings to extract (e.g. ['home', 'search']) | | raws | string[] | [] | Raw unicode characters — Fontext will resolve their ligatures automatically | | unicodeRanges | string[] | [] | Unicode ranges to extract (e.g. ['U+E000-U+E100', 'U+F000']) | | characters | string | — | Characters to keep (e.g. 'ABCabc0123') — subset engine only | | engine | Engine | 'icon' | 'icon' for ligature fonts, 'subset' for text fonts (preserves kerning) | | formats | Formats[] | all formats | Output formats: 'svg', 'ttf', 'woff', 'woff2', 'eot' | | withWhitespace | boolean | false | Include whitespace glyph in the output |

At least one of ligatures, raws, unicodeRanges, or characters must be provided.

Error Handling

extract() throws in the following cases:

• Missing or empty fontName, ligatures/raws, or formats — "Illegal option"
• Font lacks a GSUB ligature lookup table (required for raws) — "Font does not contain a GSUB ligature lookup table"
• A raw unicode character has no matching ligature — "Font does not contain a ligature for \"...\""

ExtractedResult

An object with optional keys for each requested format (svg, ttf, woff, woff2, eot), each containing a Buffer. Also includes meta and report:

interface GlyphMeta {
    name: string;      // ligature name
    unicode: string[];  // unicode mappings
    svg: string;        // SVG markup for the glyph
}

interface OptimizationReport {
    originalSize: number;  // input font size in bytes
    formats: {
        [format: string]: {
            size: number;    // output size in bytes
            saving: number;  // percentage saved (0-100)
        };
    };
}

Supported Input Formats

Single font files supported by fontkit: TTF, OTF, WOFF, WOFF2. Font collections ( TTC, DFONT) are not supported.

Browser Usage

A browser-compatible entry point is available for glyph discovery and SVG extraction (without format conversion):

import {createFont, findMetaByLigatures, findMetaByCodePoints, parseUnicodeRanges} from 'fontext/browser';

const response = await fetch('/fonts/icons.woff2');
const data = new Uint8Array(await response.arrayBuffer());

const font = createFont(data);
const meta = findMetaByLigatures(font, ['home', 'search']);
// meta[0].svg — SVG markup for the glyph

License

MIT