Creating Fonts

Use these guides when creating fonts with Font Flux JS.

Quick start

import { FontFlux } from 'font-flux-js';

const font = FontFlux.create({
	family: 'My Font',
	unitsPerEm: 1000,
	ascender: 800,
	descender: -200,
});

// .notdef and space glyphs are created automatically
font.addGlyph({
	name: 'A',
	unicode: 65,
	advanceWidth: 600,
	path: 'M 0 0 L 300 700 L 600 0 Z',
});

const buffer = font.export();

FontFlux.create() accepts family (required), plus optional style, unitsPerEm, ascender, and descender. It automatically creates .notdef and space glyphs.

Choose a target format

• Creating an OTF
• Creating a TTF

Creating glyph data

See the Creating Glyphs guide for a detailed reference on glyph metadata, outline formats (SVG path, CFF/PostScript, TrueType), and common patterns like .notdef, space, and composite glyphs.

Shared workflow

1. Create a font with FontFlux.create() or open an existing one with FontFlux.open().
2. Add glyphs with .addGlyph(), kerning with .addKerning().
3. Run .validate() frequently.
4. Export only when report.valid === true.

JSON serialization

Use .toJSON() and FontFlux.fromJSON() to safely convert fonts to and from JSON strings. This handles BigInt values (used for LONGDATETIME fields in head.created and head.modified), converts TypedArrays to plain arrays, and strips transient internal properties while preserving the data needed for lossless re-export.

import { FontFlux } from 'font-flux-js';

// Open a font
const font = FontFlux.open(buffer);

// Serialize to JSON string (for saving, transmitting, or editing)
const jsonString = font.toJSON();

// Deserialize back to a FontFlux instance
const restored = FontFlux.fromJSON(jsonString);

// Export back to binary
const binary = restored.export();

.toJSON() accepts an optional indent parameter (default 2, use 0 for compact output).

Container formats (WOFF / WOFF2)

By default, .export() outputs raw SFNT bytes. You can wrap the output in a WOFF or WOFF2 container using the format option:

import { FontFlux, initWoff2 } from 'font-flux-js';

await initWoff2(); // Required once before WOFF2 use

const woff = font.export({ format: 'woff' }); // WOFF 1.0 (zlib)
const woff2 = font.export({ format: 'woff2' }); // WOFF 2.0 (Brotli)

Fonts opened from WOFF or WOFF2 files re-export to their original format by default. Use format: 'sfnt' to force raw SFNT output.

See Validation guide and All table references.