OkFonts

Make font metrics predictable on the web. Given a font file, it adjusts vertical metrics so that:

• CSS font-size: Npx makes capitals exactly N pixels high
• CSS line-height: 1 makes single-line block elements exactly N pixels high
• Capitals are perfectly centered within their lines

It does this by setting both UPM and ascender to the font's cap height, and descender to 0. Glyph coordinates are not scaled.

Supports TTF and WOFF2.

Install

uv add okfonts

CLI

uvx okfonts input.ttf -o output.ttf

Programmatic usage

from fontTools.ttLib import TTFont
from okfonts import process

font = TTFont("input.ttf")
process(font)
font.save("output.ttf")

Public proxy

OkFonts includes a proxy server that acts as a drop-in replacement for Google Fonts. It intercepts CSS responses, downloads and processes every referenced font file, and serves the result with rewritten URLs.

A public instance is available at okfonts.matvei.is. Use it as a drop-in replacement for Google Fonts:

<link
  href="https://okfonts.matvei.is/v1/css2?family=Inter&display=swap"
  rel="stylesheet"
/>

Self-hosted proxy

Install with the proxy extra:

uv add 'okfonts[proxy]'

Run:

okfonts-proxy

The proxy exposes two routes:

• /v1/css2 — proxies CSS requests to Google Fonts
• /v1/font/{filename} — serves processed font files from cache

To use it, replace fonts.googleapis.com with your proxy host:

<link
  href="https://your-proxy/v1/css2?family=Inter&display=swap"
  rel="stylesheet"
/>

Configuration

Variable	Default	Description
PORT	3000	Port the proxy listens on
CACHE_DIR	.cache	Directory for processed fonts