Oniguruma is described as 'modern and flexible regular expressions library. It encompasses features from different regular expression implementations that traditionally exist in different languages' and is an app in the Development category. There are five alternatives to Oniguruma for Linux, Mac, Windows, Self-Hosted solutions and FreeBSD. The best alternative is Perl Compatible Regular Expressions, which is both free and Open Source. Other great apps like Oniguruma are Hyperscan (Free, Open Source), nregex (Free, Open Source), RE2 (Free, Open Source) and TRE (Free, Open Source).
The PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5. PCRE has its own native API as well as a set of wrapper functions that correspond to the POSIX regular expression API.
RE2 is a fast, safe, thread-friendly alternative to backtracking regular expression engines like those used in PCRE, Perl, and Python. It is a C++ library with wrappers for many languages including Perl, Python, Erlang and more.