idn2 - Man Page

Libidn2 Internationalized Domain Names conversion tool


idn2 [OPTION]... [STRINGS]...


The idn2 tool converts DNS domains from UTF-8 to ASCII compatible encoding (ACE) form, as used in the DNS protocol. The encoding format is the Internationalized Domain Name (IDNA2008/TR46) format.

Internationalized Domain Name (IDNA2008) convert STRINGS, or standard input.

Command line interface to the Libidn2 implementation of IDNA2008.

All strings are expected to be encoded in the locale charset.

To process a string that starts with `-', for example `-foo', use `--' to signal the end of parameters, as in `idn2 --quiet -- -foo'.

Mandatory arguments to long options are mandatory for short options too.

-h,  --help

Print help and exit

-V,  --version

Print version and exit

-d,  --decode

Decode (punycode) domain name

-l,  --lookup

Lookup domain name (default)

-r,  --register

Register label

-T,  --tr46t

Enable TR46 transitional processing

-N,  --tr46nt

Enable TR46 non-transitional processing


Disable TR46 processing


Enable STD3 ASCII rules


Disable A-label roundtrip for lookups


Print debugging information


Silent operation


Written by Simon Josefsson, Tim Ruehsen.

Reporting Bugs

Report bugs to:
Libidn2 home page: <>
General help using GNU software: <>

See Also


The full documentation for idn2 is maintained as a Texinfo manual.  If the info and idn2 programs are properly installed at your site, the command

info idn2

should give you access to the complete manual.


January 2024 Libidn2 2.3.7