The quick brown fox jumps over the lazy dog
OpenAI Sans vs Segoe UI
Two proprietary interface sans-serifs that most people meet without ever installing them. Segoe UI is Steve Matteson's humanist workhorse, Microsoft's default Windows UI face since Vista in 2007, while OpenAI Sans is the geometric brand typeface OpenAI built with ABC Dinamo for its 2025 rebrand.
OpenAI Sans is a commercial font, so it is shown here in Inter, its closest free alternative. All free alternatives to OpenAI Sans → Segoe UI is a commercial font, so it is shown here in Open Sans, its closest free alternative. All free alternatives to Segoe UI →
The quick brown fox jumps over the lazy dog
- Segoe UI is a humanist sans with open, neutral forms and true cursive italics, hinted and ClearType-tuned for small on-screen text, and it ships with Windows and Office rather than as a separate download.
- OpenAI Sans is geometric with a rounded, approachable character built around the brand's circular 'point' motif, including an O that is perfectly round outside but deliberately not inside.
- Segoe UI covers a wide range of scripts (Latin, Greek, Cyrillic, Arabic, Hebrew, Armenian, Georgian and more) in six weights from Light to Black, and Windows 11 adds Segoe UI Variable with display, text and small optical faces.
- OpenAI Sans launched in February 2025 in five core weights (Light to Bold) with italics, and OpenAI says global scripts and a monospace version are still being rolled out.
- Neither is free: Segoe UI must be licensed through Microsoft or Monotype for web and redistribution use outside Microsoft products, and OpenAI Sans is a private brand font accessed through OpenAI's design guidelines rather than sold at retail.
OpenAI Sans
Reach for OpenAI Sans only if you are working inside OpenAI's brand system, where its geometric rounded forms carry the identity; for anything else, a licensable or open geometric sans is the practical choice.
Segoe UI
Reach for Segoe UI for Windows-native apps, Office documents and dashboards, where it is already installed, battle-tested at small sizes, and metrically mirrored by the free Selawik if you need an open fallback.