Oniguruma (鬼車) is a free and open-source regular expression library that supports a variety of character encodings, written by K. Kosako.

The Ruby programming language, in version 1.9, as well as PHP's multi-byte string module (since PHP5), use Oniguruma as their regular expression engine.

[2] It is also used in products such as Atom,[3] EDK2 UEFI,[4] GyazMail, Take Command Console, Tera Term, TextMate, SubEthaEdit and jq.

There is also a forked Oniguruma version called "Onigmo" (Oniguruma-mod) which includes some features introduced in Perl 5.10+.

[7] Take Command switched back to Oniguruma in version 33 as Onigmo is no longer being updated.