Inter

It's optimized for legibility at small sizes on computer screens, with features like tabular numbers, contextual alternates, and a massive character set covering 100+ languages. SIL Open Font License (fully free for everything). Created by Rasmus Andersson (former Spotify designer). The font family includes weights from Thin to Black with matching italics. Variable font version available for fine-grained weight control.

Fully free. Use it in any project: commercial, open source, personal. No attribution required. Available on Google Fonts, npm via Fontsource, or direct download.

Inter is everywhere. GitHub uses it. Figma uses it. Thousands of web apps use it. It's become the default "safe, good" UI font choice, and that's both its strength and the only real criticism.

The catch: Inter is so widely used that it can make your app look like every other modern web app. If you want your product to have a distinct typographic identity, Inter won't give you that; it's designed to be invisible and functional, not distinctive. For dashboards, admin panels, and developer tools, that's exactly right. For a brand that needs personality, consider something with more character.