libicu

The International Components for Unicode (ICU) libraries provide
robust and full-featured Unicode services on a wide variety of
platforms. ICU supports the most current version of the Unicode
standard, and they provide support for supplementary Unicode
characters (needed for GB 18030 repertoire support).
As computing environments become more heterogeneous, software
portability becomes more important. ICU lets you produce the same
results across all the various platforms you support, without
sacrificing performance. It offers great flexibility to extend and
customize the supplied services.