Designer here: Inter is my go-to font - a free (and incredibly made!) cross between Helvetica and SF Pro! Rasmus himself has worked at his fair share of Big Important Brands (part of the original team at Spotify, worked at Facebook, NodeJS, Dropbox, Figma) [0] and it's kinda crazy to me how much Rasmus has affected me: I see the Figma icon he created every day, I see the Spotify branding he founded, I use Inter, it's kinda crazy.
Inter is the kind of font that you use when you need something that just works. Not too fancy, not too simple, it's perfect for so many things. And it's free. And it's open source [1]. What's not to like!
I beg to differ - for UX/UI, especially small screens you want large counters and tracking, as well as much higher x-heights than Inter.
It's a great general purpose font, but not the best for UX/UI. SF Pro has SF Pro Compact to deal with aforementioned issues (It is used on Apple Watch).
This is rather overstating the shortcomings for small sizes – Apple only uses SF Compact on the Watch; SF Text is used on even the smallest elements in iOS and macOS. Inter reduces approximately as well.
As for tracking, it’s already a good practice to use a slightly higher `letter-spacing` value at small sizes (something UIkit does automatically), so this isn’t really a function of the font family.
Large x-heights make me sad; I think they're helpful in screens the size of a phone or smaller, but I don't like them on desktops. Inter's x-heights are already beyond my personal aesthetic tastes.
I should clarify the purpose of x-heights and how it relates to legibility.
Taller x-heights leads to better optical legibility in small sizes.
Shorter x-heights are usually found in fonts such as Source Serif Pro for obvious reasons - it leads to be better shape recognition of the words and improved readability. Excellent in long prose and text use. Usually "Book" fonts have very short x-height. One of my favorites is Nexus Serif: https://www.martinmajoor.com/4_nexus.html
For UX/UI - ever wondered by EXIT signs are in all caps and not written as Exit? It's because of the relation of x-height to legibility at small sizes or larger distances. This is the same for avionics, warning labels, etc.
Inter isn't a good font for UX/UI IMO for the same reason why Helvetica and SF Pro aren't. They're general purpose fonts - neither good at text nor UX/UI but somewhere in the middle.
Would this be a good font to use on a small (2.8 inch) screen? I’ve got a little hobby hardware project I’m working on and am a total typography dunce.
Depends on resolution and color depth / shades of gray. If you have few pixels, and / or 1-2 of bit color depth, you may be better off with a bitmapped font.
If your display is many hundreds of pixels wide and has and several shades for antialiasing, any good font designed and hinted for screens would work.
Inter is the kind of font that you use when you need something that just works. Not too fancy, not too simple, it's perfect for so many things. And it's free. And it's open source [1]. What's not to like!
[0] https://rsms.me/work [1] https://github.com/rsms/inter
Edit: it's also not a new thing, and not a 'new SF clone' - it's been around since 2016[2].
[2] https://rsms.me/work/inter/