Ecofonts

Save Ink, Save the planet.

Ecofonts is a 100% client-side font optimizer. It punches a grid of microscopic vector holes ("eco holes") into the interior of every glyph so your documents print with less ink — up to 20% less — while staying crisp and legible at reading sizes. Everything runs in your browser: no uploads, no servers, no accounts. Your files never leave your machine.

What it does

Upload any of the following and download the optimized result with the same name and structure:

Input	What happens
.ttf / .otf / .woff / .woff2	The font's glyphs get eco holes and the font is re-compiled; web fonts come back in the container they arrived in.
.zip	Every font inside is optimized (nested folders like Google Fonts' static/ included); other files pass through untouched.
.pdf	Every embedded font — TrueType, CFF/OpenType, and legacy Type 1 — is rewritten in place; layout and selectable text stay identical.

An Eco Intensity slider (1–20%) controls how much ink is removed, and it's honest: the value maps to the measured share of glyph area actually subtracted. A minimum "wall" of ink is always preserved around every hole, so letter silhouettes are never notched and thin strokes keep their edges.

Getting started

Requires Node.js ≥ 22.12.

npm install
npm run dev       # dev server at http://localhost:4321
npm run build     # production build to ./dist/
npm run preview   # preview the production build

Routes:

• / — landing page with a drag-and-drop zone (drops are handed to the optimizer via IndexedDB and preselected there — pick an Eco Intensity and click Optimize).
• /font — the optimizer itself.

How it works

1. Parse — glyph outlines are read with opentype.js (or, for PDF-embedded fonts, directly from the font binary by format-specific parsers).
2. Flatten — Bézier curves are subdivided into polygons in integer font units.
3. Subtract — a globally aligned, staggered grid of octagonal holes is clipped against an inset of the glyph interior and subtracted with boolean geometry (clipper-lib). The inset guarantees a minimum wall thickness so outlines stay intact.
4. Re-compile — new outlines are written back into a working font binary; ZIP archives are rebuilt with JSZip and PDFs with pdf-lib, preserving structure exactly.

For PDFs, purpose-built binary "surgeons" rewrite only the outline data and keep every other byte of the font — glyph IDs, widths, encodings, and hinting of untouched glyphs — exactly as the document expects, which is what makes subset fonts without cmap/name tables work: src/lib/glyf.ts patches the glyf/loca tables of TrueType fonts, src/lib/cff.ts re-emits the Type 2 charstrings of CFF/OpenType fonts, and src/lib/type1.ts splices new charstrings into decrypted legacy Type 1 fonts.

Tech stack

• Astro (static output) + React via @astrojs/react for the optimizer UI
• opentype.js · clipper-lib · jszip · pdf-lib · woff2-encoder — all loaded on demand, so the initial page stays light
• No backend of any kind — the site deploys as plain static files

Known limitations

• Re-compiled fonts are CFF-flavored OpenType inside (an opentype.js constraint); they install and render everywhere and keep their original name and container (.woff/.woff2 uploads are re-wrapped after processing).
• Ligatures (GSUB) and variation axes are dropped from re-compiled fonts; variable fonts come back as their default instance (upload the family ZIP to keep all weights).
• In PDFs, all embedded font formats are rewritten — TrueType (FontFile2), CFF/OpenType (FontFile3), and legacy Type 1 (FontFile). Only text drawn with non-embedded viewer fonts cannot be optimized.
• Optimized files are larger than the originals (curves become line segments); that's inherent to the approach.

License note

Ecofonts modifies fonts locally and never redistributes anything, but whether you may modify a given font depends on its license. Open licenses such as the SIL Open Font License explicitly allow modification; for commercial fonts, check your license terms.

Contributing

See CONTRIBUTING.md.