FreshPlexSans is heavily based on IBM Plex Sans. Three strengths of IBM Plex Sans, which are retained in FreshPlexSans, are:

* Easily distinguishable lowercase "l" uppercase "I" and number "1".

* While not as formal as serif fonts, still suitable for serious writing.

* Exceptional overall legibility.

In FreshPlexSans, the digits "1" and "7" are less blocky than in IBM Plex Sans. For the "1" the base and the serif-like line at the top were shortened. For the "7" the serif-like line at the top was removed.