SLRE:
Super Light Regular Expression library
An ISO C library that implements a subset of Perl regular expression syntax
Simple API
Dosen’t use heap
T-Rex
A minimalistic regular expression library written in ANSI C, supports the following POSIX expressions: ?,*,+,^,$,.,[a-b],() plus the perl style greedy closures {n} . It can be conditionally compiled to support 8-bits or 16-bits character strings.
Uses heap
TRE
A lightweight, robust, and efficient POSIX compliant regexp matching library with some exciting features such as approximate (fuzzy) matching.
PCRE
Perl Compatible Regular Expressions
heavyish, fully-fledged, Unicode support, industry-standard (used in Apache etc).
RE2
C++ library
RE2 is a fast, safe, thread-friendly alternative to backtracking regular expression engines
Oniguruma:
Support different character encoding