Source Serif 4
Type with Purpose
Good typography guides attention, improves understanding, and makes communication effortless.
The Anatomy of a Typeface
By FontSide · June 2026
Every typeface is a system of decisions — about stroke contrast, x-height, spacing, and rhythm. The best ones feel invisible: you stop seeing the letters and start hearing the voice behind them. That transparency is the hardest thing to design.
A high x-height opens up the counters and makes small text breathe. Tight tracking pulls a headline together; loose tracking gives a caption room to exhale. None of these choices are accidents — they are arguments about how reading should feel.
Uppercase
Lowercase
Numerals
Symbols
Package Manager
The recommended way to use fonts in modern web projects.
1. Install Package
pnpm add @fontsource-variable/source-serif-42. Import in App
import '@fontsource-variable/source-serif-4/wght.css';3. CSS Usage
body {
font-family: "Source Serif 4 Variable", serif;
}Google Fonts CDN
Use Google's CDN to embed the fonts directly via HTML.
HTML <head>
<!-- Please select at least one weight and style -->Fontsource CDN
Skip the build step by adding this directly to your global CSS file.
Global CSS
/* source-serif-4-latin-wght-normal */
@font-face {
font-family: "Source Serif 4 Variable";
font-style: normal;
font-display: swap;
font-weight: 100 900;
src: url(https://cdn.jsdelivr.net/fontsource/fonts/source-serif-4:vf@latest/latin-wght-normal.woff2)
format("woff2-variations");
}Background & Story
Source Serif 4 is a serif typeface in the transitional style, designed to complement the Source Sans 3 family. The close companionship of Serif and Sans is achieved by a careful match of letter proportions and typographic color. Source Serif is loosely based on the work of Pierre Simon Fournier, and many idiosyncrasies typical to Fournier’s designs (like the bottom serif on the b or the middle serif on the w) are also found in Source Serif. Without being a pure historical revival, Source Serif takes cues from Fournier and reworks them for a modern age.
Both typeface families have different personalities because they spring from the hands of different designers: Source Serif was designed by Frank Grießhammer, Source Sans was designed by Paul Hunt. Robert Slimbach consulted on both designs, which helped maintain the overall family harmony. Either design feels confident on its own but also works in combination with the other — just like their designers do.
Source Serif continues Adobe’s line of high-quality open source typefaces. Designed for a digital environment, the letter shapes are simplified and highly readable. Its historical roots, combined with expert guidance give the typeface a strong character of its own that will shine when used for extended text on paper or screen.
Source Serif is an active Open Source project – if you are interested in contributing, for more information please visit github.com/adobe/source-serif-pro
Tags & Moods
Subsets
Install
pnpm add @fontsource-variable/source-serif-4Designed by
Frank Grießhammer
Links
License
OFL-1.1