Flex Sans GB

Flex Sans GB is an open-source, GB-standard sans built on IBM Plex CJK by the Flex Sans Project (a small team led by Maoken and yeshaozhile) over roughly three months of development. Building on Plex's meticulous refinements over Source Han Sans, the team reorganised the glyph set to align with the GB18030 mandatory national standard, making simplified-Chinese coverage more complete and dependable while keeping Plex's calm, modern, faintly engineered stroke character. It ships eight weights plus a variable-font build on a smooth weight axis - ideal for responsive UI, motion typography and everything from oversized headlines to body text. Under the SIL OFL 1.1 licence it is free for every commercial use (ads, packaging, film, marks, embedded apps, web), and may be modified, reused and redistributed provided derivatives stay under OFL with reserved names dropped. Download on Maoken's page; sources and licence text live in the maoken-fonts/flex-sans repository.

Government and enterprise sites, manuals, dashboards, app UI, responsive and motion typography. Prefer the variable build to pick any weight on demand; subset per weight for the web; GB18030 coverage makes simplified-Chinese documents painless.

Licence：SIL Open Font License 1.1

The dominant permissive licence for open fonts: free commercial use, modification, embedding and redistribution. Its core duties are that derivatives stay under OFL without the Reserved Font Name, the licence text travels with the files, and the fonts themselves are never sold standalone. Works typeset with them belong wholly to you.

SIL OFL 1.1. Free for every common commercial use (ads, packaging, film, marks, embedded apps, web). Modifications and redistribution must stay under OFL, include the licence text and use a new name (reserved names dropped).