Source Serif 4

Source Serif 4 is what a text serif looks like when a large, careful team maintains it for a decade. The design brief was never fashion; it was to give the Source family a serif that could carry books, documentation, interfaces, and editorial text with the same even colour. Judged on that brief it is the most complete free text serif available: optical size from 8 to 60 redraws the forms from footnote to headline, weight runs 200 to 900 for the rare system that needs a serif black, and the italics are full drawings rather than obliques.

The specification that decides real projects is language coverage. The family metadata lists Latin, Latin Extended, Greek, Cyrillic and Cyrillic Extended, and Vietnamese subsets. A publication or product shipping into Greek or Ukrainian markets usually discovers its fashionable free serif has no glyphs for the job; Source Serif 4 was built so that discovery never happens, and its Vietnamese support matches the standard set by the wider Source family.

In an editorial layout its role is the invisible one. Body text, captions, footnotes, tables, pull quotes: Source Serif 4 keeps a steady grey on the page and lets headlines and photography carry the voice. That neutrality is also its limit. Set a cover line in it and the result is correct and forgettable, which is why this directory pairs it in guidance with a display face, Playfair Display or Fraunces, rather than presenting it as a one-family answer for brands.

Production notes are brief. The full variable file is heavy with all subsets included, so subset to the scripts a project actually ships and serve WOFF2. Set font-optical-sizing to auto so the browser uses the cut drawn for each size. Static instances exist for layout tools without variable support.

The license is the SIL Open Font License 1.1, and the one condition to brief a team on is the reserved font name: Source is reserved, so a modified version of the font cannot be distributed under the Source name. Unmodified use, which is nearly every project, is unrestricted beyond keeping the copyright and license with the files and not selling the font on its own. Adobe publishes the source repository openly, and the license text travels with every download, which makes the paperwork a two-minute check rather than a procurement step. For teams standardising a publishing stack, that combination of range, coverage, and paperwork is why Source Serif 4 so often becomes the default serif everything else has to argue against.