Mainframe was created to be a relaxing monospace family. How so? The cap height is low and the spacing is generous. If you weren’t looking closely it might pass for a proportionally spaced font. Get some sweet vertical alignment going with hints of old type(writer) vibes. Pairs well with mistrust in technology. View/Download a type specimen (PDF).
In the download: 14 styles (7 weights, upright and italic) in otf/ttf/woff2 formats. License to make stuff!