The erlidna library provides a simple interface to the IDNA part of GNU libidn library implemented in NIFs.
The erlidna app is built with rebar, which must be in the command PATH.
erlidna has a very simple API. You use erlidna:encode/1 to encode internationalized domain names in ASCII strings using Punycode transcription and erlidna:decode/1 to decode back to UTF-8.
The erlidna app requires Erlang R14B or later.