mattn (Yasuhiro Matsumoto)
- title
- mattn (Yasuhiro Matsumoto)
- type
- entity
- summary
- Prolific Japanese Go and Vim open-source developer; author of many widely-depended-on Go libraries
- tags
- person, go, vim, open-source
- sources
- fsnotify-maintainer-dispute
- created
- 2026-05-12
- updated
- 2026-05-12
Yasuhiro Matsumoto, online as mattn. Japanese open-source developer with one of the largest Go-ecosystem footprints by transitive-dependency count — author of go-sqlite3, go-isatty, go-colorable, go-runewidth, and many other libraries that show up under almost every modern Go binary, plus a long catalog of Vim plugins.
GitHub: https://github.com/mattn
Tracked here for the May 2026 fsnotify maintainer dispute (see fsnotify-maintainer-dispute). The relevant facts for that incident: stepped in as maintainer after fsnotify was flagged as unmaintained by automated scanners; cut v1.10.0 and v1.10.1; the dispute with arp242 centered on a direct-to-main FUNDING.yml change and on review pace across fsnotify's many platforms. After losing org access, started gofsnotify/fsnotify as a separate implementation.
Notable translation footnote from the incident: writes Japanese natively and uses machine translation for English source-code comments and public posts. Part of the public confusion came from a machine-translated X post inserting a "we" subject the original Japanese did not have.