# mattn (Yasuhiro Matsumoto)

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.

## See also

- [[fsnotify]]
- [[arp242]]
- [[fsnotify-maintainer-dispute]]