Which fonts work best for both Android and iOS applications

I’d personally recommend using system fonts if you want a more native feel on both platforms. However, Inter is also a great choice if you want a consistent look across Android and iOS. Readability and proper spacing matter more than anything, so it’s worth testing the font on different screen sizes before making the final decision.

I've gone with Inter on a cross-platform project before and it held up well on both, the spacing stays readable at small sizes which is where I found Roboto got a bit cramped on iOS. That said, I still lean toward system fonts when the app doesn't need a strong brand look, since they follow the user's text size settings without any extra work on my end. Whichever you pick, I'd test it on a small phone with the text size bumped up, that's where the bad choices show up fast.

That way it's all on the user. We'll test with system fonts but for apps, let them choose. For web pages, go wild!

I would lean toward each platform's system font for a native feel, or Inter if you need one shared font. Either way, test at small sizes and with larger accessibility text settings, since a font that looks clean at headline size can get cramped in buttons and captions. Consistent line height matters as much as the font choice itself.