Inter Font is a Helvetica alternative typeface designed specifically for user interfaces that focus on high legibility of small-medium sized text on computer screens. This font has a long x-height to aid the legibility of mixed uppercase and lowercase text.
Various OpenType features are also provided, such as contextual alternates that adjust punctuation depending on the shape of the surrounding glyphs, italicised zero when you need to separate “0” from “o”, table numbers, etc.
Inter Font type is free for personal and commercial use.