TECkit

If your development endeavors entail implementing features that allow for encoding conversion, resorting to a software utility such as TECkit might provide you with a series of benefits.
Considering the toolkit’s main purpose, it comes as no surprise that one of the most prominent components included in TECkit works as a library that can carry out conversions. To be more specific, the so-called TECkit engine is responsible for that and also makes the testing and development of mapping tables more approachable.
The TECkit package could thus prove useful especially when trying to describe the mapping between legacy 8-bit encodings and Unicode. Aside from that, conversions can be carried out between the two.
It is worth mentioning that support for the Unicode 10.0,0 character repertoire has been implemented, so your options are quite varied.
Being a multi-platform software utility, since it supports not only Windows but also Mac OS, TECkit lets you resort to two different “languages” in order to write mapping tables. That is to mean you can choose between TECkit and XML mapping languages.
All in all, TECkit is a handy tool aimed at carrying out encoding conversions either as a standalone utility or in conjunction with third-party packages.