Source Serif (Adobe / showcase)

What’s notable: Adobe’s open-source serif (Frank Grießhammer, OFL), now in its 4th major version with a true variable axis and optical sizing. The Adobe Fonts page demonstrates the optical-size axis — display cuts have tighter spacing and higher contrast; body cuts are sturdier. The natural serif companion to Source Sans and Source Code Pro. Paired across Adobe’s own properties and adopted widely in editorial web design.

Why this matters as a reference: the open-source poster child for what a modern serif should be — variable axes, optical sizing, designed for screens, free to use and self-host.

Related

• Mona Sans showcase — sans equivalent
• Klim Type Foundry — paid commercial alternative
• transitional serif
• optical sizing
• variable font