Adobe surprised me back in 2012 when they contributed the Source Sans Pro font to the community, along with a monospaced variant called Source Code Pro. In May 2014, the Source family were joined by Source Serif Pro.
Source Serif Pro was designed by Frank Grießhammer to complement Source Sans Pro. In the blog post announcing Source Sans Pro, Nicole Miñoza writes
A careful match of letter proportions and typographic color establishes the close relationship between Sans and Serif. While attaining harmony with its Sans counterpart, Source Serif has a … unique style.
This distinctiveness has it’s roots in the work of Pierre Simon Fournier from whose work the typeface draws inspiration. Grießhammer apparently worked with Adobe’s principal type designer, Robert Slimbach on the font. Be that as it may, the end result is a good solid transitional font with a bit of personality.
It works well on screen — the designers clearly prefer digital usability to strict adherence to historical accuracy. And there are already a number of weights available, though no italics as yet, which is a shame.
The font, despite it’s origin within soulless, corporate empire Adobe is released under the free-software friendly OpenSIL licence.